We have so far registered 86,744 seafarers
| Name | Born | Place of birth (place of living shown if missing) | | David O'Connor | February 18, 1927 | Born in Belfast, Nord-Irland | |
| James O'Connor | December 25, 1915 | Lived in 10 Nilsen Street, Cardiff | |
| Michael O'Connor | April 1, 1915 | Born in Killarney | |
| Frank H. O`Donnel | February 19, 1915 | Lived in Donegal Irland | |
| George O`Donnell | May 31, 1915 | Born in Dublin | |
| John O`Grady | July 28, 1909 | Lived in Baltingglas, South-west County Wicklow, Irland | |
| Patrick O`Grady | June 22, 1911 | Born in Waterford, Irland | |
| Patrick O`Hara | December 27, 1898 | Born in Irland | |
| John O'Keefe | 1889 | Born in Cork | |
| Christopper Okufe | December 15, 1912 | Lived in 25 Coombe str. Dublin, Irland. | |
| William O'Mahoney | February 11, 1918 | Lived in O'Commel Ave., 38, Cork, Ireland | |
| Christopher O'Neill | | | |
| Eoghan O'Neill | January 2, 1922 | Born in Patrickswell | |
| Patrick O'Neill | March 18, 1912 | Born in Belfast, Nord-Irland | |
| Terence O'Neill | January 3, 1925 | Lived in 9 Wicklow Terrace, Ferry Bank Arklow Eire. | |
| William O'Neil | April 6, 1894 | Lived in Neumans, Mall, Kinsale, Cork. | |
| William O`Regan | August 15, 1914 | Lived in Cardiff | |
| Richard O`Reilly | November 13, 1916 | Born in Dublin | |
| John J. Oriaid | February 10, 1919 | | |
| Thomas Pearson | November 17, 1923 | Born in Belfast, Nord-Irland | |
| Patric Plaherty | June 12, 1920 | | |
| Michal Prendergast | December 25, 1922 | Born in Ballina | |
| Sydney Proscarth | July 31, 1925 | Born in Dublin | |
| Patrick Purdell | January 10, 1924 | Born in Waterford | |
| Patrick Reenan | 1894 | Lived in Irland | |
