Cornelius O'Callaghan, 1st Viscount Lismore
He was the son of Cornelius O'Callaghan, 1st Baron Lismore and Frances Ponsonby. He succeeded to his father's title on 12 July 1797 and assumed his seat in the Irish House of Lords. On 30 May 1806 he was created Viscount Lismore in the Peerage of Ireland.
In 1835 he was made a Member of the Privy Council of Ireland. In 1838 he was made Baron Lismore in the Peerage of the United Kingdom, giving him and his descendants an automatic seat in the British House of Lords. He served as Lord Lieutenant of Tipperary between 20 October 1851 and his death in 1857.
He married Lady Eleanor Butler, daughter of John Butler, 17th Earl of Ormonde and Lady Frances Susan Elizabeth Wandesford, on 11 August 1808. They divorced in 1826. He was succeeded in his title by his third and only surviving son, George O'Callaghan.
- Hinton, M. G. (1986). R. Thorne, (ed.). "O'CALLAGHAN, Cornelius, 1st Visct. Lismore [I] (1775-1857), of Shanbally Castle, co. Tipperary". The History of Parliament: the House of Commons 1790–1820. Boydell and Brewer. Retrieved 20 June 2014.CS1 maint: extra punctuation (link)
- Debrett's Peerage of the United Kingdom of Great Britain and Ireland, Volume 2 (1825), p.1068 (Retrieved 1 June 2016).
- Hansard 1803–2005: contributions in Parliament by Cornelius O'Callaghan, 1st Viscount Lismore
|Parliament of the United Kingdom|
| Member of Parliament for Lostwithiel
With: William Dickinson to January 1807
Charles Cockerell from January 1807
George Peter Holford
The Earl of Donoughmore
| Lord Lieutenant of Tipperary
The Viscount Lismore
|Peerage of Ireland|
|New creation|| Viscount Lismore
| Baron Lismore|
|Peerage of the United Kingdom|
|New creation|| Baron Lismore