List of The 100 characters
The 100 (pronounced The Hundred ) is an American post-apocalyptic drama television series that premiered on The CW during the 2013–14 American television season. The series is based on a book of the same name, the first in a series by Kass Morgan, and developed by Jason Rothenberg. The series premiered on Wednesday, March 19, 2014.
The following is a list of characters that have appeared on the television series. Although some are named for, or based upon, characters from Kass Morgan's The 100 novel series, there are others created solely for the television series.
|Clarke Griffin||Eliza Taylor||Main|
|Abigail "Abby" Griffin||Paige Turco||Main|
|Finn Collins||Thomas McDonell||Main||Does not appear|
|Wells Jaha||Eli Goree||Main||Guest||Does not appear|
|Octavia Blake||Marie Avgeropoulos||Main|
|Bellamy Blake||Bob Morley||Main|
|Callie "Cece" Cartwig||Kelly Hu||Main||Does not appear|
|Monty Green||Christopher Larkin||Main||Guest|
|Jasper Jordan||Devon Bostick||Main||Does not appear|
|Thelonious Jaha||Isaiah Washington||Main||Does not appear|
|Marcus Kane||Henry Ian Cusick||Main|
|Raven Reyes||Lindsey Morgan||Recurring||Main|
|Lincoln||Ricky Whittle||Recurring||Main||Does not appear|
|John Murphy||Richard Harmon||Recurring||Main|
|Roan||Zach McGowan||Does not appear||Recurring||Main||Does not appear|
|Echo/Ash||Tasya Teles||Does not appear||Guest||Recurring||Main|
|Jordan Green||Shannon Kook||Does not appear||Guest||Main|
|Hope Diyoza||Shelby Flannery||Does not appear||Guest|
|Gabriel santiago||Chuku Modu||Does not appear||Guest|
|Eric Jackson||Sachin Sahel||Recurring|
|Costa||Jojo Ahenkorah||Recurring||Does not appear|
|Bree||Alyson Bath||Guest||Does not appear||Recurring||Does not appear|
|Harper McIntyre||Chelsey Reist||Recurring||Does not appear|
|Nathan Miller||Jarod Joseph||Recurring|
|Anya||Dichen Lachman||Recurring||Does not appear|
|Connor||Josh Ssettuba||Recurring||Does not appear|
|Diana Sydney||Kate Vernon||Recurring||Does not appear|
|Fox||Genevieve Buechner||Recurring||Guest||Does not appear|
|Jacapo Sinclair||Alessandro Juliani||Recurring||Guest||Does not appear|
|Jake Griffin||Chris Browning||Recurring||Does not appear||Guest|
|John Mbege||Aaron Miko||Recurring||Does not appear||Guest||Does not appear|
|Jones||Shane Symons||Recurring||Does not appear||Guest||Does not appear|
|Kyle Wick||Steve Talley||Guest||Recurring||Does not appear|
|Shumway||Terry Chen||Recurring||Does not appear|
|Sterling||Keenan Tracey||Recurring||Does not appear|
|Zoe Monroe||Katie Stuart||Recurring||Does not appear|
|A.L.I.E. / Becca||Erica Cerra||Does not appear||Guest||Recurring||Guest|
|Byrne||Kendall Cross||Does not appear||Recurring||Does not appear|
|Cage Wallace||Johnny Whitworth||Does not appear||Recurring||Does not appear|
|Carl Emerson||Toby Levins||Does not appear||Recurring||Does not appear|
|Dante Wallace||Raymond J. Barry||Does not appear||Recurring||Does not appear|
|David Miller||Chris Shields||Does not appear||Recurring||Guest||Recurring||Does not appear|
|Emori||Luisa D'Oliveira||Does not appear||Guest||Recurring|
|Gustus||Aleks Paunovic||Does not appear||Recurring||Does not appear|
|Indra||Adina Porter||Does not appear||Recurring|
|Lee||Nick Hunnings||Does not appear||Recurring||Does not appear|
|Lexa||Alycia Debnam-Carey||Does not appear||Recurring||Does not appear|
|Lorelei Tsing||Rekha Sharma||Does not appear||Recurring||Does not appear|
|Maya Vie||Eve Harlow||Does not appear||Recurring||Does not appear||Guest|
|Nyko||Ty Olsson||Does not appear||Recurring||Guest||Does not appear|
|Vincent Vie||Ian Tracey||Does not appear||Recurring||Does not appear|
|Aden||Cory Gruter-Andrew||Does not appear||Recurring||Does not appear|
|Bryan||Jonathan Whitesell||Does not appear||Recurring||Guest||Does not appear|
|Charles Pike||Michael Beach||Does not appear||Recurring||Does not appear||Guest|
|Hannah Green||Donna Yamamoto||Does not appear||Recurring||Does not appear|
|Luna||Nadia Hilker||Does not appear||Guest||Recurring||Does not appear|
|Nia||Brenda Strong||Does not appear||Recurring||Does not appear||Guest|
|Niylah||Jessica Harmon||Does not appear||Recurring|
|Ontari||Rhiannon Fish||Does not appear||Recurring||Does not appear|
|Titus||Neil Sandilands||Does not appear||Recurring||Does not appear|
|Gaia||Tati Gabrielle||Does not appear||Recurring|
|Ilian||Chai Hansen||Does not appear||Recurring||Does not appear|
|Riley||Ben Sullivan||Does not appear||Recurring||Does not appear|
|Ethan Hardy||St. John Myers||Does not appear||Guest||Recurring||Does not appear|
|Madi Griffin||Lola Flanery||Does not appear||Guest||Recurring|
|Miles Shaw||Jordan Bolger||Does not appear||Recurring||Guest|
|Charmaine Diyoza||Ivana Milicevic||Does not appear||Recurring|
|Paxton McCreary||William Miller||Does not appear||Recurring||Does not appear|
|Kara Cooper||Kyra Zagorsky||Does not appear||Recurring||Does not appear|
|Brell||Barbara Beall||Does not appear||Recurring||Does not appear|
|Michael Vinson||Mike Dopud||Does not appear||Recurring||Does not appear|
|Josephine Lightbourne I||Sara Thompson||Does not appear||Recurring|
|Josephine Lightbourne VIII||Eliza Taylor||Does not appear||Recurring|
|Kaylee Lee VII||Sarah-Jane Redmond||Does not appear||Recurring|
|Rose||Amélie Eve||Does not appear||Recurring|
|Russell Lightbourne VII||JR Bourne||Does not appear||Recurring|
|Simone Lightbourne VI||Tattiawna Jones||Does not appear||Recurring|
|Simone Lightbourne VII||Paige Turco||Does not appear||Recurring|
|Miranda Prime VIII||Lucia Walters||Does not appear||Recurring|
|Blythe Ann Workman||Karen Holness||Does not appear||Recurring|
|Xavier / Gabriel Santiago||Chuku Modu||Does not appear||Recurring|
|Jade||Bethany Brown||Does not appear||Recurring|
|Ryker Desai IX||Thomas Cocquerel||Does not appear||Recurring|
|Delilah Workman / Priya Desai VI||Ashleigh LaThorp||Does not appear||Recurring|
|Jae Workman||Dean Marshall||Does not appear||Recurring|
|Sheidheda||Dakota Daulby||Does not appear||Recurring|
|Gavin / Marcus Kane II||Greyston Holt||Does not appear||Recurring|
- Kelly Hu was credited as main cast only in the first episode.
Sky People (also known as Arkers, or Skaikru in Trigedasleng) is a term the Grounders use for the people who came from the international space station known as the Ark. The Sky People alive today are descendants of humans who survived the nuclear apocalypse 97 years before the series by living in space in the Ark. Within the Sky People community, there is a subgroup. Known as The 100 (also known as the delinquents), this group includes one hundred juvenile delinquents who, after it became clear that the Ark was dying, were sent to Earth in order to determine if the planet had become habitable enough for the rest of the Sky People to survive in exchange for being pardoned of their crimes. However, the name the 100 is a slight misnomer, since, along with the aforementioned hundred delinquents, there were also two additional young adults who came with them to Earth; one was a security guard who snuck aboard their ship to ensure the safety of his sister, and the other was a young engineer who came down to Earth in a pod shortly afterward to reassure the council that the delinquents survived their journey.
In the sixth season, due to everything that has happened, it is revealed that there aren't many Sky People left when Abby asks for blood donations to save Marcus Kane.
Grounders (or Outsiders, as they are known by the Mountain Men) is any of the groups of people who were born on Earth rather than in space or in Mount Weather. The Grounders are descendants of humans who survived the nuclear apocalypse 97 years ago, due to their enhanced tolerance to nuclear radiation. Many of the Sky People have negative views toward Grounders, who they see as barbaric stone-age savages, just like a lot of Grounders have a negative view of The 100, who they see as hostile colonizers, though relations between the two groups are slowly improving over time. The Grounders speak an English-based pidgin language called Trigedasleng, although many of them also know regular English. Grounders were the primary antagonists of the first season. There are at least twelve Grounder clans in eastern North America, including the woods clan known as the Tree People (Trikru or Trigedakru in Trigedasleng), the dominant clan; Ice Nation (Azgeda), antagonists of the third season (along with A.L.I.E.) and the fourth; the Boat People (Floukru or Floudonkru); and other tribes such as Glowing Forest (Trishanakru), Rock Line (Boudalankru), Broadleaf (Yujleda), Blue Cliff (Ouskejonkru), Plains-riders (Ingranronakru), Shallow Valley (Louwoda-Klironkru), the Desert Clan (Sankru or Sangedakru), the Lake People (Podakru), and the Delphi (Delfikru).
Mountain Men (or Maunon in Trigedasleng) is the small colony of people who reside in Mount Weather. They are the primary antagonists of the second season. The Mountain Men (a term encompassing the women and children as well) are descendants of humans who survived the nuclear apocalypse 97 years before the start of the series by bunkering down inside Mount Weather, protecting them from the radiation caused by the bombing, but also preventing them from developing an immunity to the radiation as the Grounders did. This not only forced them to remain inside the facility unless they wore protective suits, they also had no choice but to capture Grounders and harvest their blood, which they used for transfusions to survive even the small amount of radiation exposure they received inside Mount Weather. The Mountain Men are responsible for creating the acid fog that has killed numerous outsiders, as well as the barbaric Reapers who helped them capture Grounders for their blood-harvesting program. Because so many Grounder and Arker lives were lost in the name of the Mountain Men's survival, both groups hold very negative views toward those residing in Mount Weather, although some people within the mountain actively reject treatment with the blood stolen from Grounders unless absolutely necessary, for moral reasons. In the second season, while holding forty-seven of the 100 prisoners, the Mountain Men discovered that a transfusion of bone marrow from the former Ark residents could grant them permanent immunity from the radiation, but the eventually fatal consequences for captured Arkers of the marrow-harvesting drive Clarke to a point where she is forced to open the air filtration system of the mountain, killing every one of the Mountain Men in order to save her own people. The Mountain Men are finally extinct when Clarke kills Carl Emerson, the last of the Mountain Men living in the third season.
Eligius IV prisoners
The ship Eligius IV was carrying prisoners was deployed to asteroid Proxima VI before the nuclear apocalypse on Earth happened. The purpose of the expedition was to mine Hythylodium. In 2047, the prisoners started to become sick and the captain issued "Order 11", which would abandon the prisoners on the asteroid. Out of altruistic reasons, one of the ship's pilots Miles Shaw deactivated the shock collars of prisoners that lead to the massacre of the ship's crew and an explosion that destroyed one of the engines. Led by Charmaine Diyoza, the prisoners decide to return to the post-apocalyptic Earth but with an engine destroyed, it would take decades to reach there. The prisoners put themselves through cryosleep to evade aging. In 2156, Shaw piloted the transport craft Gagarin and lands Diyoza with a party of prisoners in the Shallow Valley, which is apparently the only habitable place left after the radiation wave Praimfaya in the fourth-season finale. They act as antagonists in the fifth season and are eventually defeated, but the lives of those who surrendered are spared. The prisoners' second leader McCreary launches the Damocles bomb against Shallow Valley in an act of scorched earth, destroying the valley and rendering the Earth uninhabitable. Even decades later the Earth fails to recover and as a result, is deemed permanently uninhabitable.
Wonkru is a new, united clan, consisting of the former 12 Grounder clans and Skaikru, founded by Octavia Blake. Later, they are now led by the new Commander, named Madi.
These citizens live in a settlement, called Sanctum, which is on a habitable moon, called Alpha. They're led by the ruling families, known as the Primes, with their leader, Russell Lightbourne. At the end of season six, the citizens revolt against the Primes, some of whom are killed with most of the citizens surviving.
Children of Gabriel
The Children of Gabriel is a rebel militia group, who are in conflict with the Primes, the twelve quasi-immortal leaders of Sanctum. They were founded by Gabriel Santiago, also known as the Old Man, who was once the Thirteenth Prime but rebelled seventy years before the present after recognizing the immorality of what the Primes were doing. Gabriel is known as a demon to the people of Sanctum and an almost mythical figure amongst his followers, having been missing for ten years. Unknown to the Children of Gabriel, Gabriel has been hiding amongst them as Xavier, a high-ranking and less extreme member of the organization, having been unwillingly resurrected in Xavier's body after his last host died.
Portrayed by Eliza Taylor, Clarke Griffin is the daughter of Abigail Griffin and Jake Griffin, and the effective leader of the 100 for much of the series. Her backstory is that she was imprisoned as an accessory to the crimes of her father after attempting to inform their people that the Ark was dying, and thus ended up among the 100. Down on the ground, she tries to ensure the 100's survival by assisting in the acquisition of food and resources, and she also continuously serves as their main medic before her mother and the other medical staff join them on Earth. She is portrayed as relatively benevolent, but has been shown to act ruthlessly to fight or kill in order to protect her people if there are no other options, and she possesses natural leadership qualities with the help (and early on, the opposition) of Bellamy. They learn to love each other. After killing the entire Mountain Men population to save her fellow Sky People, Clarke becomes known in Trigedasleng as Wanheda (literally "Death-commander") and is sometimes also called Mountain-slayer. Clarke becomes gradually hardened and matured by her experiences on Earth, namely the acts she has been forced to commit to survive and protect her people. This transforms her into a strong but personally troubled heroine in the series, as she continues to struggle to reunify humankind by maintaining the uneasy peace between the Arkers and some of the Grounders, and between groups among her own people. On February 28, 2015, the series creator Jason Rothenberg confirmed that Clarke is bisexual; this makes her the first openly bisexual lead character on the CW network. In the sixth season, Clarke's body is possessed by the consciousness of Josephine Lightbourne, but Clarke herself survives a mind wipe due to a remnant of the A.L.I.E. AI. Josephine later relinquishes control to Clarke to escape a decapitation though the two continue to share her body. After Josephine manages to remain inside of Clarke's body even after the Mind Drive is removed, Clarke destroys Josephine's consciousness for good and regains full permanent control of her body. Shortly afterwards, Clarke loses her mother when Abby is mind-wiped to become the new host for Josephine's mother, Simone. Clarke is subsequently forced to blow Simone and anything left of Abby into space in self-defense, something that, along with her adopted daughter Madi becoming possessed by the Dark Commander, causes her to almost commit suicide.
Portrayed by Bob Morley, Bellamy Blake is the Co-leader of the 100, leader of the Skaikru and The Heart in the lead dynamic[The Head and The Heart] of the show. He's also Octavia's brother and the best friend, soulmate of Clarke Griffin. He professes a strong determination to protect his sister, spanning from her birth. He often says "my sister, my responsibility". He was the leader of the 100 and described as the one who inspires masses. He's often inspired by Clarke after a tumultuous start to their relationship. He and Clarke develop a mutual respect and learn to compromise for each other's methods. He still feels guilty for his mother's death.
In second season he went undercover in Mt Weather, which was a huge risk, to save 40 of his people who were held captive to extract their Bone Marrow. In the end he along with Clarke were able to save all of their people although they had to pull the lever that radiated all of the people in Mt. Weather after the betrayal by Lexa.
In the third season, he saw Clarke while she was a prisoner of Roan. In order to save her he took a huge risk by dressing as a grounder and crossed an army of grounders in order to retrieve Clarke but his attempt resulted in him being knocked out. Clarke sacrificed her freedom to prevent him from getting killed. He was manipulated by the new Chancellor after Azgeda (Ice Nation) bombed Mt Weather, killing 49 people, including his girlfriend. In the process, he betrays Marcus Kane and put the whole of The Ark at risk of death. The bombing was made possible because Bellamy trusted Echo, the Grounder he saved in the previous season in Mt Weather. He listened to the false information she delivered in order to save Clarke. After Pike's election, Bellamy is one of the nine guards (along with Pike himself) that carry out the chancellor's orders to kill the 299 Grounder warriors sent by Lexa. Bellamy soon feels guilt for his actions, and while he saves Indra's life, this puts a rift between him and Octavia, as well as Kane. He remains one of the few people not taken over by A.L.I.E., and fights alongside Octavia and Pike to stop her.
In season 4, he saved his people, including Riley, who were held as slaves by an Ice Nation gang. His determination to save his people often puts him in danger. Afterward, he reconciled with Kane. He is often on the grounders' side, feeling it is selfish for the Sky People to hog all the places in the bunker. In S4 finale he had to leave Clarke behind on the ground in order to reach the Ark.
In the fifth season, it is revealed he survived on the Ark in space. After being reunited with Octavia, he feels he does not recognize her anymore due to her brutal and unforgiving ways, but still tries to get through to her. It was also his idea to try and take the cryogenically frozen prisoners hostage and have leverage with Diyoza in order to save Clarke. He also made Madi realize that they had made mistakes and asked her to forgive the Eligius crew and they all boarded the ship at his request. Also, his denial to board the ship without all of his people on board indicated his PTSD regarding leaving Clarke behind in S4 finale. He also poisoned his own sister to spare Clarke's life thus indicating a shift in his priority.
In the 6th season he's still feeling guilt over Monty and Harper's along with several of his friend's death which resulted in a conflict between him and Echo. When Clarke was body-snatched by The Primes it was him who recognized it wasn't her in Clarke's body which resulted in him being knocked out. He's also the one who learns Clarke is still alive inside her Brain based on the Morse code. He risks everything and everyone's life to save Clarke and his relationship with Clarke was described as weird by Josephine. In the end he performed CPR and desperately asked Clarke to fight for her life which resulted in her revival. In the season finale he watched in horror as Octavia was snatched from his hands by the anomaly.
Portrayed by Kelly Hu, Callie "Cece" Cartwig (season 1) is the best friend of Abigail Griffin as well as the Ark's communications officer. Callie is first seen talking to the people on The Ark about the 100 going down to Earth. She said that she cannot confirm or deny anything at the moment. When Callie comes to know that Abigail Griffin is going to be executed she goes up to Marcus Kane to tell him that he is out of his mind and he cannot kill everyone who disagrees with him. Callie says that Abigail is her friend leaving Kane to reply that he cannot do anything to stop it. Kane and Callie share a close moment. She tries to implore him to give Abby amnesty, asking him to think of their own relationship. He answers by saying that no matter what he feels, he cannot. When it is time, Callie breaks into tears walking with Abigail to the place where she will be executed, embracing her and refusing to let go even at the behest of the guards. Abby asks that Callie watch out for her daughter before she dies. When the door is about to close Chancellor Thelonious Jaha demands the execution be stopped immediately. Callie is thrilled for Abigail, able to hold her friend again. Jason Rothenberg revealed that Hu was dropped after the first episode due to budget reasons.
Portrayed by Paige Turco, Abigail "Abby" Griffin (seasons 1-6) is Clarke's mother. She is the chief medical officer of the Ark and the main proponent regarding the habitable status of Earth. Her husband was the chief engineer, Jake Griffin. She was a member of the Council led by Chancellor Jaha on the Ark before being stripped of her title, though she regained this position shortly afterward. Upon her arrival on Earth, Abby was Chancellor for a time when Marcus Kane gave her his pin. During this time she ruled autocratically, refusing to let Kane take over again on his return and betraying her former friend Jaha by putting him in prison. Abby becomes friends with Raven Reyes when she needs her mechanical expertise to try to get more information on what the 100 is dealing with on the ground. She begins to like the young engineer due to her reminding her of Clarke. Abby's relationship with her daughter became strained following Clarke's discovery of her mother's betrayal to her father which led to his execution. It only became more complicated once Abby and the rest of the people from the Ark joined the 100 on Earth, as they were both the leaders of their respective groups of people. Abby continues to work as the resident doctor in the newly established Sky People colony known as Arkadia (formally Camp Jaha) and has supported Marcus Kane's campaign for peaceful cohabitation with the Grounders, putting her at odds with the anti-Grounder factions within their people.
In season six's "Adjustment Protocol", Abby becomes a Nightblood to help save Clarke's adopted daughter Madi. Abby is subsequently mind-wiped by Russell Lightbourne, effectively killing her and her body becomes the new host for Simone Lightbourne. In "The Blood of Sanctum", Clarke holds out hope that Abby survived in the same way that she did, but Russell confirms that Abby is truly gone. After a failed attempt by Simone to pose as Abby, Clarke blows Simone and several others out into space, killing them all. Abby's body is last seen floating away into deep space.
Portrayed by Thomas McDonell, Finn Collins (seasons 1–2) is a caring teenager who is always looking for fun and a peaceful solution. He is more interested in helping others than seeking vengeance. He was arrested for being a spacewalker and wasting the Ark's limited oxygen supply, but it was revealed that he was innocent and had taken the fall for Raven, his girlfriend, to ensure she did not ruin her engineering career or get floated. Originally Clarke's love interest, Finn's relationship with Clarke starts collapsing when she discovers his relationship with Raven. His romances with both girls ultimately end, but Finn and Clarke still love each other, and Raven still loves Finn. In the second season, his fear that Clarke has been killed by her captors in addition to the hardships he has endured cause him to become unpredictable and violent. He murders eighteen unarmed Grounders who he believed had taken Clarke hostage, and was willingly going to leave several fellow Arkers for dead in favor of continuing his search for her. As a result of his actions, the Grounders demanded retribution before they will agree to a truce between them and the Sky People, leading Commander Lexa to sentence Finn to death by a thousand cuts. However, he was mercifully killed by Clarke to prevent the Grounders from slowly and painfully killing him, though he did appear one last time during Clarke's grief-induced hallucinations.
Portrayed by Eli Goree, Wells Jaha (season 1; guest season 2) was Clarke's childhood best friend and the son of Thelonious Jaha, who was the Ark's Chancellor at the start of the series. He is despised by some of the 100 upon landing on the ground because of his father. He intentionally committed a crime when he found out about the imminent launch of the delinquents to Earth so as to join the group in the hope to protect Clarke, for whom he harbors feelings. Clarke believed he was the reason her father is dead, only to find out later that her mother was the one who betrayed her father, and Wells willingly took the blame to prevent Clarke from hating her. On the ground, he is hardworking and thoughtful, volunteering to dig graves and collect rainwater to aid their newly established colony. It was his expert knowledge of botany that made him a valuable ally to Clarke, as she was tasked as the 100's medic due to her previous experience as the daughter of a doctor and needed herbal medicines to treat the ill and injured members of their community. He was murdered by Charlotte in the third episode, who wanted retribution for his father's execution of her parents on the Ark. He appears once again in the second season, when a hypoxic Thelonious hallucinates that Wells is alive and with him on the Ark, when everyone else has left for the surface. When Thelonious falls under A.L.I.E.'s influence, he forgets about Wells and has to be reminded by A.L.I.E., causing Abby to realize that something is wrong with him.
Portrayed by Marie Avgeropoulos (and by Olivia Steele Falconer as child) Octavia Blake is Bellamy's younger sister – a rare relationship given the Ark's one-child rule. She was kept a secret by her family, living under the floor to avoid detection by authorities, but was eventually caught when Bellamy snuck her out of her room to attend a masked ball. Once discovered, some of the detainees discriminate against her for being a second child and thus an outcast to the Ark's dystopian society. She is a fiercely independent girl who is constantly rebelling and getting attention from men, most notably the Grounder Lincoln. However, just like Clarke, she is not exactly built for war so she is horrified at what she sees and experiences at first. In the second season, she becomes more immersed in Grounder culture and serves as Indra's second. Originally she felt hatred towards Clarke for being the daughter of someone in the same council who had her locked up. It is intensified when she discovers Clarke knew about the bombing of Tondc, did nothing about it, and allowed all those Grounders to die after the events of Mount Weather (even telling Indra that she will not leave behind Bellamy and her friends). She remains in her Grounder gear, and berates Lincoln for wearing an Ark jacket and for being naive as she still holds a grudge towards them. Eventually, Lincoln is brutally killed in front of her by Pike, causing a rift between her and Bellamy. In the fourth season, she shows more signs of being bloodthirsty after killing an ambassador who questions Roan's leadership. This new violent attitude earned her the nickname Skairipa ('Sky-reaper') or Death from Above. After refusing to kill Illian and getting close with him she decides to drop the act and take him home. She later accepts the fact that she is a killer and will fight in the Grounder battle for the bunker alongside Trikru, in which she is victorious after killing Luna, and becoming the acting leader of all 12 clans by telling them they will share the bunker. She finally forgives Bellamy for Lincoln's death after he opened the bunker realizing that he would put his own life in danger just to save her and the Grounders. She later protects Nilyah and further solidified her role as new leader by saying if Skaikru does not choose the 100 people to stay in the bunker then she will kill every Skaikru member. In the season finale, she officially becomes the new leader of the new Grounder tribe consisting of Skaikru, Trikru, Azgeda, and other Grounder clans, regardless of her blood and what is in her head. In the fifth season, although still reluctant on being the leader, she tries to make peace with everyone. Eventually, overpopulation prevents from any real peace inside the bunker, so Octavia takes matters into her own hands and kills anyone who defies her or questions her view of what peace should be. Thus covering herself in their blood and being told by Gaia that it is best she keeps the blood on her, thus becoming Bloodreina (the Red Queen) and decides anyone who breaks her laws must compete in deathmatches. During two years in the bunker, Abby's actions caused Octavia to become more dark and hateful that led to her ruthless actions as ruler of Wonkru, including murdering anyone who tries to defect, killing some of her own people in order to force them to stay alive when the only source of protein is their own dead, and culminating in her burning down the Hydrofarm in the bunker in order to force a conflict for the Shadow Valley rather than negotiating peace. Near the fifth season finale, she later has a change of heart, after realizing that she broke Wonkru. In the season finale, a remorseful Octavia unexpectedly helps Abby save Kane's life after a confrontation between the two women in which Octavia appeared to be torn between leaving or killing Kane. In the sixth season, she is exiled on Sanctum by Bellamy and works with Diyoza who was also exiled. After being poisoned, Octavia seeks healing from the mysterious anomaly with the help of Gabriel Santiago. After being healed, Octavia decides to seek redemption for her actions and declares herself Bloodreina no more. At the end of season six, Octavia is stabbed by Diyoza's adult daughter Hope and disappears into the anomaly again, leaving her fate unknown.
Portrayed by Christopher Larkin, Monty Green (seasons 1–5, guest season 6) is a smart and tech-savvy teenager who is a valuable asset to the teens on Earth due to his pharmaceutical and engineering knowledge. He and Jasper were arrested for making illegal substances. He is best friends with Jasper and is among the 48 held in Mount Weather; he eventually escapes and reunites with his mother in the third season. He tries to help Jasper recover from the traumatic events in Mount Weather. He eventually becomes part of Chancellor Pike's cause after his friend Monroe is killed by the Grounders. In the process, he gets Marcus Kane put in prison and Lincoln killed. He eventually betrays his mother and Pike in "Stealing Fire" by helping Kane, Octavia, Harper, Miller, and Sinclair escape by feeding members of the Ark Guard faulty intel and distracting them. In "Nevermore", Monty is forced to kill his mother—who had taken A.L.I.E.'s key—after she nearly kills Octavia. In "Red Sky At Morning", Monty has sex with Harper in Arkadia, and is forced to delete and essentially kill his mother for a second time by wiping her memory from the City of Light. In the fourth season, he comes up with the idea of protecting his people by shielding Arkadia with a hydrogen generator and recruits Bellamy, Harper and Miller to procure it. When they do, they blow it up to rescue the slaves taken by the Ice Nation. There he learns that the Chief had killed his father and, instead of Monty killing him himself, he allows the slaves vengeance by freeing them. After realizing that Harper chose to stay behind in Arkadia, he decides to stay with her until she changes her mind; she is eventually convinced and they search for more people to recruit. In the fifth season, he is still with Harper but feels guilty about killing his mother and letting Jasper commit suicide. By the end of the season, it is revealed that he died with Harper after growing old together and raising their son, Jordan. 125 years after they had entered cryo sleep, the survivors of Earth are greeted by Jordan, who shows them Monty's video logs, which reveal that Earth is completely uninhabitable, but that Monty had found them a new habitable planet on which to live.
In the sixth season, though he is dead, Monty returns as a manifestation of Clarke's mind in "Nevermind". Monty appears as Clarke is giving up the fight to encourage her to keep going and helps Clarke access Josephine's most traumatizing memory in an effort to regain some control over Clarke's body. Though they fail to stop Josephine, Monty helps Clarke send Bellamy a Morse code message, revealing that she is still alive by discreetly taking control of one of Clarke's fingers.
Portrayed by Devon Bostick, Jasper Jordan (seasons 1–4) is a goofy and geeky chemist. He is Monty's best friend. After his capture and subsequent rescue from Grounders, he becomes traumatized by his near-death experience which he struggles to overcome. Early in the series, he has a crush on Octavia, even saving her life during an animal attack, but she offers her friendship in return instead. He was one of the delinquents' camp's gunners and is among the 48 held in Mount Weather, and becomes an acting leader of his surviving people in Clarke's and Bellamy's absences. Jasper later becomes romantically involved with a Mount Weather resident, Maya who was later killed. In grief, Jasper becomes an alcoholic and he is disgusted that his own people would steal from Mount Weather after the war with its inhabitants as well as hating Clarke. Monty and Octavia struggle to help Jasper to cope with his loss, but although Jasper was briefly tempted by the City of Light tablets, when he realised that they erased all good memories relating to painful topics, he refused to take one, even breaking Raven out of Camp Jaha and taking her to Clarke and other escapees for medical treatment to remove the chip. It is revealed that he has been chipped while on Luna's oil rig and turns on the 100 under A.L.I.E.'s command. He is freed from her control once she is defeated. In the fourth season, he attempts suicide only for Raven to tell him they only have six months to live. He eventually commits suicide by remaining at Arkadia and taking an overdose of hallucinogenic nuts, convincing several other people to join him. Monty attempts to save Jasper as the death wave approaches, but can only be at his side as he dies. In the fifth season, Clarke recovers Jasper's goggles and suicide note from the ruins of Arkadia and Monty learns that Jasper had been intending to commit suicide since he emerged from the City of Light and held a belief that they ruin everything around them. Monty and Harper later name their son Jordan Jasper Green in Jasper's honor.
Portrayed by Isaiah Washington, Thelonious Jaha, commonly referred to as "Jaha" (seasons 1–5) is Wells' father and the former Chancellor of the Ark. Jaha, along with Marcus, were best friends with Jake Griffin and his family. However, his and Marcus' friendship with the Griffins deteriorates after Jake's death and Clarke's subsequent arrest but he manages to maintain his friendship with Abby. He loses his power while on Earth as he clashes with Abby and Marcus over their views on the Grounders in addition to the unconfirmed destination, the "City of Light". Along with Murphy, he leads a small group of his followers from Camp Jaha to find the city. Having discovered A.L.I.E., the artificial intelligence that controls the City of Light, Jaha has become the delegated leader of A.L.I.E.'s cult, manipulating others into joining to escape the pain of daily life. Jaha is unconcerned about the side-effects even when presented with clear evidence that the City of Light erases even good memories to spare the users from psychological pain, such as Jaha having lost all memory of his son, he is soon freed from A.L.I.E.'s control after her defeat. He becomes guilt-ridden after he sees all the casualties in Polis due to him feeding everyone a chip. In the fourth season, he assists Clarke in being a leader for her people such as suggesting they find shelter in a lost bunker, only to discover it could not hold out radiation. Jaha tells everyone that if they want to survive the second nuclear explosion they must earn a lottery pick to ensure they will be on that list. He eventually comes to the realization the bunker was a decoy and the real one is in Polis, the Grounder capital, so he decides to recruit Gaia on what she knows about the symbol on the token and eventually learns it is a key to open the bunker. He eventually finds it and successfully opens it, he takes a child after promising his father to take care of him. In the fifth season, he is stabbed by an Azgeda Warrior and dies in front of Kane, Abby, and Octavia.
Portrayed by Henry Ian Cusick, Marcus Kane is one of the Councillors on the Ark. When Thelonious Jaha was Chancellor, he was second-in-command. He, along with Jaha, were friends with Jake Griffin and his family, but his friendship with them did not last after Jake's execution and Clarke's subsequent arrest. Though he initially supports population culls to extend life on the Ark, when Earth is shown to be survivable, he is guilt-stricken and works with everyone to survive in hopes of making amends of his past misdeeds. This, in addition to his mother's influence and death, affect his later actions of seeking peaceful and compromising solutions when governing his people after arriving on Earth. In the process, he gains allies who respect his new approaches, rebuilds his friendship with Jake's wife Abby Griffin, and earns the Grounders commander Lexa's trust. Kane aligns himself with Abby, who becomes Jaha's successor. In the fifth season, six years after Praimfaya he takes the fall for Abby's crime and proceeds to fight in gladiator battles but refuses once Octavia shows signs of being a dictator. After being severely injured in the fifth season finale, he is put into stasis and remains there in the sixth season after a failed attempt to save his life. Kane's mind is eventually transferred into the body of a young man named Gavin to save his life, erasing Gavin's mind in the process. In "What You Take With You", Kane decides to commit suicide rather than continuing to live in someone else's body. After awakening Indra and leading a coup against the Primes on Eligius IV, Kane says a final goodbye to Abby before having Indra blow him out of an airlock along with the new Nightblood serum. In "Adjustment Protocol", when Abby is mind-wiped to become the new host of Simone Lightbourne, she remembers Kane in her last moments alongside her daughter and deceased husband.
Portrayed by Lindsey Morgan, Raven Reyes (season 2–present; recurring season 1) is an ambitious zero-gravity mechanic when on board the Ark who is not afraid of anyone or anything. She later collaborates with Abby Griffin in her escape from the Ark and launches herself in a pod to Earth, and occasionally advises Abby in the fields in electronics and mechanical engineering after she becomes chancellor on Earth. Brave and intelligent, Raven leads the camp in setting up communications and making bombs. She was childhood friends with Finn and was in a relationship with him until he fell in love with Clarke. It is revealed in the second season, that Finn took the blame for Raven's crime because she was already 18 and would be floated. She was the first zero G mech student under the age of 18 in 52 years. In the third season, with Abby's help, Raven begins recovering from the injuries she sustained from last season. She joins Jaha's cause after reluctantly taking a tablet given to her by him, she does begin to fight the side effects after Jasper reminds her about Finn. She is soon saved by Clarke and freed of A.L.I.E.'s control. In the fourth season, she bonds with Luna for her loss and convinces her to help save everyone on Earth, she also forgives Murphy for shooting her in the spine. It is revealed while taking the chip she is able to use 90% of her brain but developed a tumor that could cause her to have a stroke, possibly leading to her death. She later hallucinates Becca who tempts her with the chance to spacewalk leaving her to stay behind. A Sinclair hallucination appears to tell her to continue living which gives her the motivation to fight off Becca by restarting her heart. Afterwards, Clarke rescues her and request she fly them to The Ark in which she agrees to do, and successfully able to fly them to space and finally was able to spacewalk again. In the fifth season, Raven becomes an improved fighter being able to topple Echo in combat and plans to return to earth she soon notices another ship landing on Earth, and proceeds to follow it, she realizes there are other life forms in cryostasis on the Eligius ship and decides to stay behind and lies about an escape pod so Bellamy will not argue with her.
Portrayed by Ricky Whittle, Lincoln (seasons 2–3; recurring season 1) is a Grounder who rescues Octavia. The pair develop a romantic relationship, and Lincoln helps the 100 multiple times, causing him to be viewed as a traitor to his people. He later is drugged to become a reaper, but with Clarke's and Abby's assistance, he is successfully rehabilitated from the drug. Having been viewed as a traitor by some of his people, Lincoln resides in Camp Jaha with Octavia. He is put in prison by Pike with the help of Bellamy and shot by Pike after surrendering to save his fellow Grounders from execution.
Portrayed by Richard Harmon, John Murphy (season 3–present; recurring seasons 1–2) starts out as one of Bellamy's men and is generally disliked by the group due to his reputation of being a troublemaker and career criminal, making him one of the few members to actually have committed felonies and not petty misdemeanors. After being wrongfully accused by Clarke and nearly lynched, he tries to kill Charlotte. As a result of her suicide, he is banished from the camp. He later returns, surviving being tortured by the Grounders. He seems to have forgiven the 100, but he kills two and attempts to hang Bellamy and accidentally shoots Raven in the spine. In the second season, he helps the 100 as they search for their lost members, even saving Bellamy's life when he could have let him drop. As he is still disliked in Camp Jaha, he accompanies Jaha to find the City of Light. He eventually finds a lighthouse where he is trapped by Jaha and A.L.I.E. after watching something that horrifies him (later revealed to be a video that shows that A.L.I.E. caused the nuclear holocaust). He later leaves the island after not wanting to be a part of Jaha's insane missions, and gets a boat ride from Emori. After Emori transports him and Jaha across the sea, he refuses to take the key and flees with Emori. They start robbing people in the Commander's Forrest and he is eventually captured by Grounder warriors and brought to Polis, as one of the captors discovers a chip in his pocket which has the "Sacred Symbol of the Commander". He is tortured for information by Titus and eventually tells him what he knows. After seeing an escape pod marked Polaris with the a and r burned off as well as drawings, Murphy pieces together the story of the First Commander Becca and her connection to The Ark. Later on, Titus tries to murder him and frame Clarke but accidentally shoots and kills Lexa. After she dies he witnesses Titus remove the chip. After Titus gives Clarke the chip and commits suicide, Ontari makes him the new "Flamekeeper" since he is the only other person to have witnessed it being removed from another person. Ontari takes a liking to him and wants him to sleep with her; if he refuses, she will kill him. He later reunites with Emori who is under A.L.I.E.'s control, and A.L.I.E. implies to her that Ontari's had sex with him. During the final battle with A.L.I.E., Murphy plays a vital part by manually pumping the brain-dead Ontari's heart to keep a blood transfusion to Clarke going so that she can use the Flame to destroy A.L.I.E. After the City of Light is destroyed and A.L.I.E.'s control over everyone dissolves, Murphy stays behind with Emori. When he finds out there's a nuclear disaster coming which will wipe out everyone on Earth, he and Emori decide to side with Clarke, who has a plan that might save 100 people. Murphy ends up helping Raven with another plan, and he is confronted with what he is put her through after he shot her. When Raven opts to stay behind, he has a rare emotional moment and shares a tearful goodbye with her. In the fifth season, six years after Praimfaya, he breaks up with Emori suffers an inferiority complex, as they land on the Eligius ship before Bellamy and the others land on Earth, he decides to stay on the ship to protect Raven only for her to berate him by telling him she lied about the escape pod, much to his dismay. In the sixth season, Murphy allies himself with the Primes on Sanctum after being offered immortality for himself and Emori despite the Primes killing Clarke to become Josephine Lightbourne's new host. Murphy finds himself torn between his friends and immortality, particularly due to his fears of what awaits him after death. Though Murphy gains the chance to become a Prime and immortal, he turns his back on the Primes after losing both Abby and Clarke in favor of saving his people with Emori. Clarke, who survived and had been posing as Josephine, admits that she is proud of him, causing Murphy to realize that his friend is still alive. Murphy and Emori manage to rescue their friends and Murphy aids Gabriel Santiago in subduing the Sanctum citizens who have been driven insane by the Red Sun toxin, helping to prevent the massacre of innocent people. During this time, Murphy meets Zev, the male lover of Daniel Lee who Murphy is impersonating. Murphy's reaction to Zev suggests that Murphy may not be strictly heterosexual, though this is unconfirmed.
Portrayed by Zach McGowan, Roan (season 4; recurring season 3) is an Ice Nation fugitive who is tempted by Lexa to kidnap Clarke. He turns out to be Prince Roan, son of Queen Nia. He later becomes king of the Ice Nation after Lexa kills Nia for attempting to overthrow her. He supports Ontari as the new Commander and attempts to track down Clarke who has escaped with the Flame. Roan and Clarke instead form an alliance to give Ontari the Flame to help shut down A.L.I.E. but the plan fails and Roan is shot by Kane. He is rescued when Clarke and Abby take the bullet out of his chest. Echo tries to tempt him to kill Clarke for her crimes as well as secure his position as ruler of the 13 clans. However, Clarke gives him A.L.I.E. 2.0 in hopes that he will let her and her people live to save the planet from the nuclear explosion in 6 months which he accepts. Later, he learns that Skaikru seems to be protecting themselves thus ending the alliance. Clarke convinces Roan to share Arkadia until it explodes. He takes part in the challenge where each tribe sends a champion to fight for the position of the leader – who gets to decide which tribe survives in the bunker. He banishes Echo for trying to cheat in the tournament, and declines to fight Octavia, whom he respects. In the end he is killed by the Nightblood Luna, who drowns him.
Portrayed by Tasya Teles, Echo (season 5–present; guest seasons 2–3; recurring season 4) is a former Ice Nation Grounder who was trapped at Mount Weather. She saves Bellamy's life, which leads him to trust her and he helps her escape. She later betrays him and helps act out a plan that led to the destruction of Mount Weather. After the events in the City of Light she blames Skaikru for all the casualties and demands for Clarke's execution. She becomes a royal guard and the bodyguard of Roan, but is banished for her interference in the Grounder battle. She assists Octavia in trying to open the bunker, but Octavia will only help Azgeda and not her. She fights off Grounders who tried to kill Clarke and provides protection onward in exchange for her safety when the death wave hits. In the season finale, Bellamy talks Echo out of suicide and she joins Bellamy's group in retreating to the remains of the Ark in space. In the fifth season, six years later, she is romantically involved with Bellamy, and afraid to return to earth knowing Octavia will want her dead. Once she returns to earth she is confronted by Octavia who reminds her of her banishment but gives her an ultimatum on spying on the people of Eligius IV in exchange for banishment being lifted, and Octavia executes several of her people to make her defection seem legitimate.
In season six's "Ashes to Ashes", it is revealed that the real Echo is dead. The current Echo is her best friend Ash who was forced to kill Echo as a child and take her place by Queen Nia of the Ice Nation. In the same episode, Echo becomes a Nightblood after being injected with Madi's bone marrow, narrowly escaping being mind-wiped with the help of Gaia and Nathan Miller. Echo helps to build a rebellion against the Primes and joins her friends in trying to do better by saving as many people as they can from a psychosis-induced massacre created by the Primes releasing a toxin into the population.
Portrayed by Shannon Kook, Jordan Green (season 6–present; guest season 5) is the son of Monty Green and Harper McIntyre.
- Jarod Joseph as Nathan Miller: One of the 100. He was among the surviving 47 held in Mount Weather in the second season. While in Mount Weather, it is revealed that Miller was arrested on the Ark for thievery. He is able to escape Mount Weather and is reunited with his father at the end of the second season, who was the head security guard on the Ark. In the first episode of the third season, Miller is reacquainted with Bryan, his boyfriend. He becomes a member of Arkadia's Guard but secretly sided with Kane alongside Harper as they tried to overthrow Chancellor Pike. He is one of the few Skaikru members who did not take A.L.I.E.'s chip to join the City of Light, and survives the battle in Polis in the season finale. In season five, he has entered a relationship with Jackson.
- Chelsey Reist as Harper McIntyre (seasons 1–5): One of the 100. She had a crush on Jasper at the beginning of the first season, although it ended up going nowhere. She is among the 47 held in Mount Weather in the second season, and was the first to have her bone marrow forcibly extracted from her. She and Monty are the only two who survived having their bone marrow extracted. After escaping and returning to Arkadia, she joins Arkadia's Guard and secretly sides with Kane alongside Miller as they tried to overthrow Chancellor Pike. She is one of the few members of Skaikru who did not take A.L.I.E.'s chip to join the City of Light. She sleeps with Monty in the third season, and is saved by him in the season finale when a chipped Jasper knocks her unconscious and takes her hostage in Arkadia. In the fourth season, after feeling she sacrificed one of her own for her own survival she decides to stay behind with Jasper and Monty. She eventually comes to her senses and goes with Monty to recruit as many people to join them in the bunker. By the end of the fifth season, it is revealed that she died of a genetic condition after growing old with Monty and raising their son, Jordan.
- Katie Stuart as Zoe Monroe (seasons 1–3): One of the 100 who suffocated to death in a Grounder village after escaping a fire in the third season.
- Keenan Tracey as Sterling (seasons 1–2): One of the 100. He fell to his death trying to rescue his friend Mel, who was the sole survivor when her section of the Ark crash-landed.
- Genevieve Buechner as Fox (seasons 1–2): One of the 100. She is among the 47 held in Mount Weather. She was nearly killed for her bone marrow in Mount Weather, but Bellamy saves her. She is killed shortly after anyway for her bone marrow.
- Rhys Ward as Atom (season 1): One of the 100 who was an adviser to Bellamy and became romantically involved with Octavia. He was severely burned by the acid fog and Clarke killed him out of mercy.
- Izabela Vidovic as Charlotte (season 1): One of the youngest members of the 100, who was arrested for attacking a guard. She has recurring nightmares about Chancellor Jaha executing her parents. She attempts to stifle the nightmares by killing his son, Wells, but later breaks down and confesses before jumping off a cliff to her death. Despite murdering her best friend, Clarke chose to protect Charlotte from the more aggressive members of the group who wished to kill her, and banished Murphy because of her death.
- Brendan Meyer as Myles (season 1): One of the 100, who was killed by John Murphy for his part in the attempted lynching against Murphy.
- Josh Ssettuba as Connor (season 1): One of the 100, who was killed by John Murphy for his part in the attempted lynching against Murphy.
- Sachin Sahel as Eric Jackson: Abby's helper and confidant. In the third season, he is taken over by A.L.I.E. He is freed from A.L.I.E.'s control once Clarke defeats her. In the fifth season, he has entered a relationship with Miller.
- Alessandro Juliani as Jacapo Sinclair (seasons 1–4): a technician who was a father figure and mentor to Raven. He was later killed in the third season by Emerson. He later appears in the fourth season as one of Raven's hallucinations.
- Steve Talley as Kyle Wick (seasons 1–2): An engineer who was a coworker of Raven back on the ark. They later engage in a relationship. He also became friends with Marcus Kane after he saved him. In the third season, it is mentioned that he and Raven have broken up.
- Chris Browning as Jake Griffin (season 1, 6): Abby's husband and Clarke's father who died prior to the beginning of the series. He was executed for attempting to release critical information regarding the Ark's swiftly deteriorating life-support systems; Clarke initially blamed Wells for telling his father, before learning that her mother was responsible and Wells took responsibility to save her relationship with her mother. Clarke was accused of assisting in his crime. A manifestation of Jake appears in Clarke's mindspace in the sixth season when she is trapped in her own mind by the implantation of Josephine Lightbourne's Mind Drive. In her last moments, Abby remembers her husband alongside Marcus Kane and her daughter.
- Terry Chen as Commander Shumway (season 1): Loyal to Diana Sydney. His plan to have Bellamy assassinate Jaha is later revealed, and Shumway is killed on Diana's orders.
- Kate Vernon as Diana Sydney (season 1): A former Chancellor of the Ark who was behind the assassination attempt on Jaha, having had Shumway recruit Bellamy for the job. After Abby Griffin is stripped of her council seat, it is given to Diana. She and her team steal and launch the Exodus ship to Earth, Diana painting herself as a voice of the "lower classes" who would otherwise not be given the chance to return to Earth as the Ark's resources are depleted. The ship crash lands and she is killed upon impact along with her accomplices. It is later revealed that Mount Weather caused the Exodus ship to crash.
- Kendall Cross as Major Byrne (season 2): Captain of Marcus Kane's guard at Camp Jaha. She is killed by a mutated species of carnivorous ape.
- Michael Beach as Charles Pike (seasons 3, 6): An Ark survivor from Farm Station. On the Ark he was a teacher, but on Earth he is a leader in the guard and later the chancellor of Arkadia. He is captured and sent to be executed for his crimes against the Grounders. In the season finale, after assisting in defeating A.L.I.E., he is stabbed to death by Octavia to avenge Lincoln's death. In the sixth season, Pike reappears as a manifestation of Octavia's mind after she takes the Red Sun toxin.
- Jonathan Whitesell as Bryan (seasons 3–4): The former boyfriend of Nathan Miller from Farm Station. He is one of the few Skaikru members who did not take A.L.I.E.'s chip to join the City of Light, and survives the battle in Polis in the season finale. In the fourth season, Bryan destroys a hydro generator in order to free some slaves and he later breaks up with Miller because he did not believe saving the slaves was the right decision. His current fate is unknown, but he likely died in the death wave as Bryan has not been seen since.
- Donna Yamamoto as Hannah Green (season 3): Mother of Monty and an Ark survivor from Farm Station, she is under A.L.I.E.'s control and shot by Monty while trying to rescue Octavia. After being used by the AI as a distraction in the City of Light, she is reluctantly deleted by her son and Raven Reyes.
Trikru (Tree People)
- Alycia Debnam-Carey as Lexa (seasons 2–3): The Commander of the allied Grounder clans. She is willing to negotiate with the people of the Ark so they can save their people in Mount Weather and agrees to an alliance once Finn is dead. She views love as a weakness, and revealed that she previously had a girlfriend named Costia who was killed by the Ice Nation. Despite this, she allowed the Ice Nation into her coalition. She develops romantic feelings for Clarke, however, after a kiss, betrays her and Skaikru to save the imprisoned Grounders from the Mountain Men. She later sends Roan to find Clarke and bring her to Polis. She swears loyalty to Clarke after Skaikru are initiated as the thirteenth clan. Clarke goes to Lexa to say goodbye, where they confess their feelings for each other. Soon after, she is killed when she rushes into Clarke's room after hearing gunshots, only to get caught in Titus's crossfire. She returns via A.L.I.E. 2.0 to assist Clarke in defeating A.L.I.E. and says goodbye to her to help fight off A.L.I.E.'s henchmen so Clarke can find the kill switch. Her memories and persona remain a part of the Flame, through which she later offers guidance to its new host Madi, who gains a fresh perspective on the events prior to the death wave. Thanks to Lexa's memories of betraying Clarke at Mount Weather, which Madi describes as her greatest regret, Madi is able to dissuade Clarke from abandoning Wonkru to be wiped out in order to protect Madi. The current state of her consciousness is unknown as Raven was forced to delete the Flame at the end of season six, but at least the mind of the Dark Commander was uploaded to an unknown location.
- Dichen Lachman as Anya (seasons 1–2): The leader of one of the Grounder clans, and the main antagonist of the first season. In the second season, she is held captive in Mount Weather with Clarke who forms a reluctant alliance with Anya to escape. Clarke subsequently seeks her help in making peace with the Grounders, but she was killed by the guards of Camp Jaha because the guards thought she was a threat. She used to be a friend and mentor to Lexa before she became the Commander.
- Joseph Gatt as Tristan (seasons 1–2): A military leader of the Grounders. He led the attack on the 100 and was one of the few to survive the ring of fire. At the beginning of season two, after ambushing the few who escaped Mount Weather's roundup, he was shot by Marcus Kane.
- Adina Porter as Indra (season 2–present): A leader of one of the Grounder clans who considers Lincoln a traitor to her people. In the second season, she appoints Octavia as her second after being impressed by her bravery. In the fourth season, it is revealed she had a daughter named Gaia who refused to follow her mother's cause and learned to be a Flamekeeper. In the fifth season, she shows disapproval in the death games Octavia has arranged, admitting that the person Octavia has become scares her. Indra soon allies with Clarke and Bellamy to try to overthrow Octavia and prevent the impending war for the Shallow Valley, without success. She is awakened from cryo in season six to help deal with the situation with the Primes. She reveals that she once saw the Dark Commander as a child and knows the evil and chaos he can create.
- Ty Olsson as Nyko (seasons 2–4): A healer of the Grounders and considered Lincoln's brother because of their true friendship. He first appears to help save Octavia from a poisoned wound and due to his relationship with Lincoln, remains a friend and ally of the Sky People. He is killed by a drone who guns him down while trying to protect Luna.
- Jessica Harmon as Niylah (season 3–present): A Grounder who owned and operated a trading post. She helps Clarke to escape from the Ice Nation bounty hunters. Niylah later sleeps with Clarke and becomes her lover. Later, she helps Clarke to free Raven of A.L.I.E.'s control. Clarke thanks her and tells her to hide until the time that A.L.I.E. is defeated. In the fourth season, after A.L.I.E.'s defeat by Clarke, Niylah comes to Arkadia to live close to her, but it was destroyed soon after by Ilian who blames Skaikru for the death of his family killed by him while under A.L.I.E.'s control. However, Ilian saves Octavia and Niylah from the resultant inferno and Clarke resumes her romantic relationship with Niylah and persuades her to remain in Arkadia. Later, Niylah goes with Clarke in the Second Dawn Bunker to be in safety. During the time where Clarke leads a group to save Raven, Niylah is attacked by some Sky People but is saved by Octavia who takes her in as part of her inner circle of associates for Niylah's own protection.
- Neil Sandilands as Titus (season 3): An Old Guard who serves as an advisor to Lexa. His official position is as the Flamekeeper until he passes the title on to Clarke. He kills himself in order to prevent Ontari from becoming the new commander.
- Cory Gruter-Andrew as Aden (season 3): A Nightblood trained by Lexa. Aden is seen as polite and genuine when he speaks with Clarke about what should happen if he becomes Heda. He seems to care about Lexa, as seen in the episode "Watch the Thrones" as he corrects her when she asks him to tell Clarke what will happen when he becomes Heda; Aden responds saying if he becomes Heda. He is decapitated by Ontari in his sleep.
- Tati Gabrielle as Gaia (season 4–present): Indra's daughter and Titus' apprentice, who becomes the new Flamekeeper following the defeat of A.L.I.E. She has a strained relationship with her mother, who resents her for becoming a religious fanatic rather than a warrior, but they make amends as the death wave grows nearer. Gaia becomes a faithful follower of Octavia, guiding her to become the Red Queen, but becomes disillusioned with her methods and eventually persuades Madi to accept the Flame and become Commander, with Indra and Bellamy's help. All three are arrested for treason and sentenced to fight in Wonkru's gladiatorial games by Octavia, but after Monty provokes a brief uprising, Octavia pardons them. Gaia participates in Wonkru's invasion in the Shallow Valley, where she is wounded in an ambush by the Eligius convicts, but she survives. In the sixth season, she is banished on Sanctum by Madi at the urging of the Dark Commander after failing to stop him from negatively influencing Madi. Despite this, she remains loyal to Madi and works with the others to save Madi and create a rebellion against the Primes on Sanctum.
Azgeda (Ice Nation)
- Brenda Strong as Queen Nia (seasons 3, 6): The former queen of the Ice Nation who killed Costia (former lover of Lexa) and attempted to overthrow Lexa, but was murdered at her hand. She later appears in a flashback in the sixth season where it is revealed that after Echo's best friend Ash killed the real Echo in self-defense, Nia forced Ash to take Echo's place and identity.
- Rhiannon Fish as Ontari (season 3): A Nightblood who served as the bodyguard for Queen Nia and later King Roan of Ice Nation. She succeeded Lexa as the new Commander after murdering the other Nightbloods. Due to her brutal nature Titus is hesitant to implant her with the Flame, which is actually an A.I. implanted in all commanders and gives it to Clarke who escapes Polis. Due to the requirement of having the Flame implanted to be commander, Ontari conceals this from the Grounder ambassadors with only Roan and Murphy aware of the truth. Later on, she seduces Murphy to sleep with her under threat. Afterward, she takes the chip given to her by Jaha in the hope that it will grant the knowledge of the past commanders. Later, A.L.I.E. decides that she cannot risk losing control of Ontari, the last of the Nightbloods, and orders Jaha to kill her. Though she survives, Ontari suffers brain damage and is unable to accept the Flame. Instead, she is used as part of a blood transfusion directly with her heart to allow Clarke to accept the Flame. She dies soon after Clarke destroys A.L.I.E., once Murphy stopped pumping her heart.
- Luisa D'Oliveira as Emori (season 2–present): A nomadic Grounder who scours the wastelands in search of the City of Light. Emori and her brother later rob Jaha and his group for their supplies, and later meets up with Jaha and Murphy at the City of Light. When she returns to see Murphy, it is revealed that she is under A.L.I.E.'s control. She is freed when the City of Light is destroyed and joins Bellamy's group on the Ark monitoring station in the six years following the death wave, during which Raven teaches her technological skills and she and Murphy break up. After reaching Sanctum in season six, Murphy proposes to Emori using two Mind Drives and she accepts his proposal.
- Finn Wolfhard as Zoran (season 2): A deformed, nomadic Grounder boy who helps Jaha after he reaches Earth, until his father sells Jaha in exchange for horses so the family can search for the City of Light.
- Nadia Hilker as Luna (seasons 3–4): The Nightblood leader of the Sea People and the main antagonist of the fourth season. She fled her conclave to avoid further killing, allowing Lexa to become Commander. Clarke, Bellamy, Octavia and Jasper try to persuade her to accept the Flame following Lexa's death, so they can defeat A.L.I.E., but she refuses. Her people later die from radiation poisoning and she allies with the Sky People to find a way to recreate Nightblood and save humankind from the death wave, but after Emori is almost sacrificed for their experiments, Luna becomes disillusioned and nihilistic, believing the human race should end. She fights in the conclave for the Second Dawn Bunker, intending that no-one will occupy it if she wins, and is one of the last competitors standing. After she kills Roan, Octavia outwits and kills her. Luna was perhaps the greatest warrior alive, and has implied that had she stayed and competed in the conclave she would have won, even against Lexa (whose fighting skill is renowned). Roan only defeated Luna when she was wounded, while Octavia's victory against her was due to cunning and deceit rather than superior skill but finally they reconciled.
- Lola Flanery as Madi Griffin (season 4–present): A 12-year-old Nightblood who Clarke meets 58 days after Praimfaya. The two become friends and Clarke begins to look after her. She is in effect Clarke's adopted daughter and has accepted the Flame to become the new Commander. However, in season 6, she falls under the influence of the spirit of the Dark Commander, an evil and insane previous Commander who, in the past, has been held at bay by the spirits of the other Commanders. At the end of the season, Madi breaks free of his control, but Raven is forced to delete the Flame to save her life. However, the Dark Commander survives by uploading himself to an unknown location.
- Raymond J. Barry as Dante Wallace (season 2): The leader and president of the Mount Weather colony, who favours more diplomatic attempts to use the blood of the 100 to cure his peoples' own vulnerability to radiation. He is eventually ousted from his leadership role. He is killed when Clarke shoots him in the chest.
- Eve Harlow as Maya Vie (seasons 2, 6): A resident at Mount Weather who develops romantic feelings toward Jasper. Though initially unaware of Mount Weather's true intentions, she eventually realizes what is going on and assists Bellamy in his attempt to rescue the 47. She eventually joins a rebel faction of her people in hopes of overthrowing the Mount Weather government and helping Jasper. While trying to help Octavia, she is killed when Clarke releases radiation on the fifth floor. Having fallen in love with Maya, her death drives Jasper to depression and he becomes suicidal. Maya later appears in the sixth season as a manifestation in Clarke's mindspace after she becomes trapped when Josephine Lightbourne's Mind Drive is implanted into her. Maya confronts Clarke over her actions and later helps Clarke to temporarily trap Josephine before disappearing.
- Rekha Sharma as Dr. Lorelei Tsing (season 2): One of the doctors at the Mount Weather colony. She uses the 47 to extract their bone marrow in order to get to the ground with no remorse. She is killed when Bellamy exposes her and several guards to radiation, and when she tries to escape via an elevator; Jasper, Monty, Miller, and Harper stop her from escaping and watch her die.
- Johnny Whitworth as Cage Wallace (season 2): The son of Dante Wallace, and the main antagonist of the second season. He works on the Cerberus Project and plans to kill the 47 to save himself and everyone else. He later betrays his father when he tries to release the 47. When his people are dying of radiation, Lincoln cuts off his hand and injects him with the Cerberus Serum, killing him.
- Ian Tracey as Vincent Vie (season 2): Maya's father who is with her on assisting the 47 and leads a rebel faction. He is killed by one of the Mount Weather guards.
- Toby Levins as Carl Emerson (seasons 2–3): A Mount Weather guard and the right-hand man of Cage Wallace. He is captured by Clarke for information on Mount Weather but is sent back to tell Cage that she and the Grounders are coming. He becomes one of the few to receive the bone marrow transplant that allows the Mountain Men to survive in the outside world. He is the sole surviving resident of Mount Weather, after Clarke and Bellamy irradiate the fortress and kill the rest of the Mountain Men to save the captive Arkers. He aligns himself with the Ice Nation and provides the self-destruct codes used to blow up Mount Weather, having lost his entire family when Mount Weather was irradiated. After Roan becomes king, Emerson is given to Clarke and Lexa as a peace offering. After long consideration Clarke spares him to show the other Grounders vengeance is not the answer. He returns to seek vengeance against Clarke and her friends, but Clarke manages to implant him with the Flame which can only be used by Nightbloods. As a result, Emerson's brain liquifies in seconds, killing him and ending the Mountain Men.
City of Light
- Erica Cerra as A.L.I.E. / Becca Franko (seasons 2–6):
- A.L.I.E.: The avatar of an artificial intelligence who guides Jaha and Murphy to the City of Light and is the main antagonist of the third season. A.L.I.E. is responsible for causing the nuclear apocalypse 97 years ago (revealed to be on May 10, 2052). A.L.I.E. had come to believe that the problem was "too many people" and initiated the apocalypse to solve this problem. She uses computer chips to take control of peoples' minds as well as tempt others into doing her bidding such as Jaha wanting to lead his people, Raven wanting to stop feeling pain, and Ontari wanting to know the knowledge of previous commanders. She also tends to physically and psychologically harm them if they disobey her. At the end of the third season, Clarke Griffin, protected by the A.L.I.E. 2.0 AI, confronts A.L.I.E. in the City of Light on a manifestation of the space station Polaris. A.L.I.E. reveals that her actions have been to save humanity from a coming second nuclear apocalypse caused by the meltdown of power plants across the world that survived the bombing. Though Clarke attempts to get A.L.I.E. to give people a choice instead of using force, her programing prevents it. Clarke destroys A.L.I.E. by activating her kill switch, but believes the AI's warnings about the coming disaster, later confirmed by Raven Reyes. A.L.I.E. appears briefly in flashbacks at the beginning of the fourth season when Becca makes an appearance in Raven's hallucinations. In the sixth season, a manifestation of A.L.I.E. appears in Clarke's mind to explain that Clarke still has a part of the AI inside of her from when Clarke entered the City of Light. As a result, Clarke's mind was protected from erasure when Josephine Lightbourne's Mind Drive was implanted. The manifestation of A.L.I.E. helps Clarke to hide the knowledge of how to get rid of Clarke's consciousness permanently.
- Becca Franko: Becca was a brilliant scientist who created the AI's A.L.I.E. and A.L.I.E. 2.0. Another innovation of Becca was Nightblood which she created to allow humans to metabolize extreme levels of radiation. However, Becca became concerned upon learning that A.L.I.E. thought the problem with humanity was "too many people" and locked the AI away which proved to be a grievous mistake. As Becca worked on A.L.I.E. 2.0 on her space station Polaris, A.L.I.E. escaped and began a nuclear holocaust that destroyed humanity. Despite this, Becca continued her work on A.L.I.E. 2.0 for another two years, believing the second AI to be humanity's best hope of survival. After the Polaris Commander demanded the destruction of A.L.I.E. 2.0, Becca fled Polaris in an escape pod as the station was destroyed. Having injected herself with Nightblood and A.L.I.E. 2.0, Becca became known as Pramheda, or "First-commander" in Trigedasleng due to arriving on Earth in the spacesuit of the Polaris Commander. Becca passed on Nightblood to the people she met upon landing, but was eventually burned alive by the Second Dawn cultists with the AI, which eventually became known as the Flame, being passed down to future Commanders. Like all Commanders, Becca's spirit was preserved within the AI and was able to help guide her successors. Becca appears mainly in flashbacks and hallucinations in the third and fourth seasons. At the end of the third season, Becca's spirit appears to Clarke Griffin through the Flame to guide Clarke in shutting down A.L.I.E. once and for all. When Clarke tried to reason with A.L.I.E., Becca informed Clarke that the AI could not change her way of doing things as her programing didn't allow it and witnessed as Clarke activated A.L.I.E.'s kill switch. In the fourth season, her lab and Nightblood research become a vital part of the attempt to survive the coming death wave. According to Gaia, Becca is buried in the Second Dawn bunker. In the sixth season, Becca is revealed to have created the Mind Drives that allow the Primes of Sanctum to be reincarnated through various new hosts when they die, the Mind Drives being similar to the Flame but without the artificial intelligence. At the end of the sixth season, the state of her consciousness that was saved in the Flame is unknown as the Flame was deleted, but the Dark Commander at least was uploaded to an unknown location.
- James Neate as Chris (seasons 2–3): One of the few scientists who helped create A.L.I.E. At the end of the second season, John Murphy finds a recording of Chris in the lighthouse bunker blaming himself for the nuclear apocalypse and A.L.I.E.'s actions before he commits suicide out of guilt. In a flashback in the third season, Chris contacts Becca on Polaris to warn her that A.L.I.E. has escaped and is accessing nuclear launch codes. With Chris unable to stop A.L.I.E. and the nuclear apocalypse beginning, Becca orders him to the bunker for his own safety.
- Ivana Milicevic as Charmaine Diyoza (season 5–present): The ruthless leader of the Eligius spaceship that arrives in the Shallow Valley six years after Praimfaya. She is a former U.S. Navy SEAL Colonel-turned-terrorist who was arrested and cryogenically frozen for her crimes for over 100 years before the nuclear apocalypse that wiped out most of the population on Earth. She has escaped captivity by murdering the original captain of the Eligius ship, and has become the leader of the group of convicts aboard Elgius. She invades the Shallow Valley with her equally ruthless army and captures Clarke, but is coerced into freeing Clarke and rescuing Octavia and everyone in the bunker after being forced into a deal with Bellamy after Raven took control of the Eligius. Diyoza is revealed to be pregnant with McCreary's child, which is the only reason he spares her life after usurping leadership of the convicts. In the sixth season, she is exiled on Sanctum and works with Octavia who is also exiled. After being led to the anomaly, Diyoza is drawn inside by a hallucination of her child, leaving her fate unknown. Octavia later tells Bellamy that she is dead, swallowed by the anomaly. In the season finale, Diyoza's daughter Hope, now an adult despite only days passing, emerges from the anomaly and states that "he" has her mother before stabbing Octavia who disappears with the anomaly.
- William Miller as Paxton McCreary (season 5): A brutal serial killer who is among those who have arrived on Earth aboard the Eligius spaceship after being cryogenically frozen for over 100 years and also has little knowledge of what happened on planet Earth after the nuclear apocalypse. He secretly wishes to replace Diyoza as leader of the convicts, but his methods demonstrate a fundamental reliance on violence, favouring killing potential enemies as the first option. He eventually usurps Diyoza but spares her life after learning she is pregnant with his daughter, and he forms tentative alliances with Clarke and Kane to win the war, though he intends to completely wipe out Wonkru. He becomes the new leader of the Eligius prisoners but is later killed by Miles Shaw and Clarke Griffin. However, as his last act, McCreary launches the Damocles bomb which destroys the valley, the last habitable place on Earth as an act of scorched earth. McCreary's destruction of the valley proves to be too much for Earth which never recovers and is left completely uninhabitable even decades later.
- Jordan Bolger as Miles Shaw (seasons 5–6): The pilot of the convict ship who is among those who have arrived on Earth aboard the Eligius ship. He has shown a greater willingness to negotiate with the survivors found on Earth as opposed to the convicts' willingness to kill as the first option, and he ultimately rebels against Diyoza and McCreary, allying with Echo's group to help Wonkru win the war and developing a romance with Raven. He is killed by the radiation fences on Sanctum during the eclipse.
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