Spyros Stavros "Spiros" Niarchos (Greek: Σπύρος Νιάρχος; born 1955) is the second son of the Greek shipping magnate Stavros Niarchos and Eugenia Livanos. He is a grandson of another Greek shipping giant, his mother's father, Stavros G. Livanos.
In 1987, while skiing in Switzerland, he met 19-year-old Daphne Guinness (artist, socialite and an heiress of the Guinness family) and they soon married. The marriage ended in divorce, with Guinness receiving a GBP 20 million settlement in 1999.
The couple has three children:
- Nicolas Stavros Niarchos (born 1989)
- Alexis "Lex" Spyros Niarchos (born 1991)
- Ines Sophia Niarchos (born 1995)
In January 1999, Niarchos was a witness at the wedding of his best friend, Ernst August, Prince of Hanover. He is the godfather of Crown Prince Pavlos' youngest son, Aristides-Stavros. With his brother, Philip, Niarchos is co-president and member of the board of directors at the Stavros Niarchos Foundation.
- Corlett, Ewan (1981). The Revolution in Merchant Shipping 1950–1980. The Ship. series editor: Basil Greenhill. London: Her Majesty's Stationery Office on behalf of the National Maritime Museum. p. 25. ISBN 0-11-290320-7.
- Meare, David. "Tirgoviste and Spyros Niarchos". Shipspotting.com. Retrieved 30 April 2013.
- "Heiress apparent". The Sunday Times. 21 October 2007.