 | O'Sullivan, Patrick | | |  |
| O'Brien, Joseph Somerton | 09-04-1912 | 07-09-1940 |  |
| O'Brien, Patrick | | |  |
| O'Conner, Edward | 00-00-1923 | |     |
| O'Connor, David | | |  |
| O'Connor, Edward | 00-00-1923 | | |
| O'Driscoll, Finan | 18-07-1916 | 16-01-1942 |   |
| O'Flaherty, Laurence James | | | |
| O'Grady, Arthur Edward | | |  |
| O'Hare, Patrick John | | |  |
| O'Leary, Arthur Alexander | 04-01-1921 | 21-04-1987 |  |
 | O'Meara, James Joseph | 20-02-1919 | 04-06-1974 |  more |
| O'Neill, Hugh Francis 'Peggy' | 00-00-1920 | |   more |
| O'Neill, James | | |  |
| O'Neill, John Joseph | | |  |
| O'Sullivan, Hugh Barry | | 00-07-1956 |  |
| Oakes, Eric Raymond | | | |
| Oatts, John Douglas | | 26-11-1941 |  |
| Odd, Ronald William | | | |
 | Odgers, Sydney Edward | | |     more |
| Ogburn, Eric Frank | | 15-12-1946 | |
| Ogilvie, Donald Gordon | 03-11-1916 | 13-06-1943 | |
| Ogilvie, Patrick Bruce Bine | 14-01-1910 | 11-12-1944 | |
| Ogilvy, Charles Alexander "Alastair" | 30-11-1915 | 23-02-1995 |  |
| Oldham, Douglas Edward | | |  |
 | Olivant, Cecil Herbert | 22-07-1901 | 27-08-1941 |    |
 | Olivant, Richard John | 07-12-1887 | 19-06-1981 |    more |
| Oliver, Claude Danolds | 29-12-1903 | 27-09-1987 |  |
 | Oliver, Frederick Emmanuel | 19-08-1924 | 25-11-1968 | |
| Oliver, Geoffrey Nigel | 22-01-1898 | 26-05-1980 |   more |
 | Oliver, George William | 00-00-1904 | | |
| Oliver, George William RAF | | | |
| Oliver, William Padfield | | |   |
| Olver, Harry Vernon | 18-03-1892 | 25-08-1943 | |
 | Olver, Peter | | | |
| Onslow, Richard George | 00-00-1904 | 16-12-1975 |  |
| Oram, Harry Percy Kendall | 23-10-1894 | 00-11-1988 | |
| Ord, Robert Edward | 16-09-1917 | 05-09-2004 | |
| Ormiston, Frederick | | | |
| Orpen, Walter David | | 22-03-1942 | |
| Orr, Cecil William Bannon | | |  |
| Orr, Hubert Gerald | | 25-09-1944 | |
| Orr, Stanley Gordon | 28-09-1916 | 11-08-2003 |   |
 | Orton, Newell "Fanny" | 00-00-1915 | 17-09-1941 | |
 | Orwin, Peter Francis Barclay | | 18-08-1941 |  |
| Osborne, Gordon | | | |
| Osborne, Lionel Russell | | | |
| Osborne, Vincent Arthur | | | |
| Oswick, John Roger Gunston | 26-11-1921 | 26-08-2016 | |
| Otway, Terence Brandram Hastings | 15-06-1914 | 23-07-2006 |  |
| Outfin, Richard Malherbe | 00-00-1908 | 29-04-1944 | |
| Ouvry, John Garnault Delahaize | | | |
| Ovans, Michael Edward | 00-00-1911 | | |
| Overton, Frederick | | | |
| Owen, Brian John Francis | 23-08-1922 | 15-10-1992 | |
| Owen, Charles Maxwell | | | |
| Owen, Derek Edward | | 04-10-1946 | |
 | Owen, Sidney Edward | | 28-10-1944 | |
| Owen, William Aston | | | |
| Oxborrow, John Edgar Percival | 09-01-1922 | 12-09-1944 | |
| Oxley, Leonard Ernest | | | |
| Oxspring, Robert Wardlow "Oxo" | 22-05-1919 | 08-08-1989 | more |
