Cornelius O'Callaghan
Cornelius O'Callaghan may refer to:
- Cornelius O'Callaghan (died 1742), Irish politician, MP for Fethard 1723–1714
- Cornelius O'Callaghan (1712–1781), Irish politician, MP for Fethard 1761–1768, for Newtownards
- Cornelius O'Callaghan, 1st Baron Lismore, Irish politician and peer, MP for Fethard, Tipperary 1768–1785
- Cornelius O'Callaghan, 1st Viscount Lismore, Irish peer and privy counsellor, MP for Lostwithiel 1806–1807
- Cornelius O'Callaghan (1809–1849), Irish politician, MP for Tipperary 1832–1835
- Cornelius O'Callaghan (Fianna Fáil politician), Fianna Fáil senator 1970–1974