Agents persons, peoples and institutions
- 1927–1991
- 1701–1769
- 1896–1962
O'Brien (Paul) ... Irish priest See: Pól Ó Briain
O'Clery (Michael) See: Mícheál Ó Cléirigh
O'Connell (John) See: Seághan Ó Conuill
O'Connell (Peter) See: Peadar Ó Conaill [d. 1826]
- ?–1732
- fl. 18th century
- s. xx–xxi
- 1710–1791
- Belanagare
O'Conor (Charles) ... of Belanagare See: Charles O'Conor [of Ballinagare]
- 1764–1828
- b. 1794–d. 1862
O'Daly (Aengus) See: Aonghus Ruadh Ó Dálaigh
O'Daly (Hugh) See: Aodh Ó Dálaigh
- 1800–1878
- Dublin, Farlane ... Co. Waterford