Alexander Martin Sullivan, SL was an Irish lawyer, best known as the leading counsel for the defence in the 1916 treason trial of Roger Casement. He was the last barrister in either Ireland or England to hold the rank of serjeant-at-law, hence his nickname The Last Serjeant.
- Occupation
- barrister, journalist
- Position held
- King's Counsel, serjeant-at-law
- Citizenship
- United Kingdom of Great Britain and Ireland, Irish Free State, Ireland