| Surname | First name | Played | Points | Last appearance |
|---|---|---|---|---|
| O'Brien | Sean | 2 | 0 | 15/08/2020 |
| O'Callaghan | Donncha | 55 +4 | 5 | 28/04/2018 |
| O'Connell | Jack | 2 +7 | 10 | 06/05/2017 |
| O'Connell | Ken | 11 | 0 | 20/02/1998 |
| O'Connor | Brendon | 46 +7 | 40 | 18/05/2019 |
| O'Connor | James | 35 +4 | 115 | 18/05/2019 |
| O'Connor | Johnny | 40 +10 | 15 | 15/04/2007 |
| O'Connor | Shane | 0 +1 | 0 | 03/10/2009 |
| O'Conor | Piers | 34 +4 | 50 | 13/09/2020 |
| O'Cuinneagain | Dion | 27 +6 | 30 | 08/05/1999 |
| O'Donnell | Rob | 10 +19 | 0 | 08/03/2015 |
| O'Donoghue | Eddie | 6 +14 | 0 | 24/03/2012 |
| O'Driscoll | Billy | 0 | 0 | 00/00/0000 |
| O'Flaherty | Tom | 23 +3 | 40 | 04/09/2020 |
| O'Grady | Dylan | 11 +2 | 0 | 17/05/1998 |
| O'Keefe | Martin | 0 | 0 | 17/11/2002 |
| O'Kelly | Malcolm | 33 +1 | 10 | 23/01/1999 |
| O'Leary | Daren | 96 +9 | 148 | 30/04/2005 |
| O'Leary | Tomas | 28 +11 | 5 | 09/05/2015 |
| O'Mahony | Darragh | 109 +9 | 170 | 08/05/2004 |
| O'Neill | Ryan | 21 +6 | 20 | 09/02/2002 |
| O'Neill | Steve | 23 +10 | 5 | 21/05/2000 |
| O'Reilly | John | 4 +11 | 0 | 12/05/2002 |
| O'Riordan | Brian | 18 +5 | 5 | 09/03/2008 |
| O'Shea | Conor | 66 | 195 | 25/11/2000 |
| O'Shea | Darren | 0 +1 | 0 | 10/01/2016 |
| Oakes | Jason | 18 +3 | 0 | 21/10/2007 |
| Oakley | Rhys | 53 +26 | 15 | 23/02/2013 |
| Obano | Beno | 37 +29 | 15 | 22/09/2020 |
| Obatoyinbo | Elliott | 4 +4 | 5 | 13/09/2020 |
| Obi | Nnamdi | 0 | 0 | 00/00/0000 |
| Odejobi | Mark | 0 | 0 | 27/09/2009 |
| Odogwu | Paolo | 14 +7 | 10 | 05/09/2020 |
| Oduoza | Uche | 3 +1 | 0 | 07/05/2011 |
| Oelofse | JJ | 0 | 0 | 15/11/1998 |
| Offiah | Martin | 1 +6 | 15 | 12/05/2002 |
| Officer | David | 22 +7 | 25 | 24/04/2000 |
| Oghre | Gabriel | 2 +11 | 15 | 13/09/2020 |
| Ogilvie | Phil | 5 +13 | 10 | 14/11/1999 |
| Ogilvie-Bull | James | 2 +1 | 10 | 10/09/2000 |
| Ojo | Topsy | 171 +17 | 230 | 28/10/2017 |
| Ojomoh | Steve | 61 +15 | 35 | 16/04/2001 |
| Okafor | John | 0 | 0 | 00/00/0000 |
| Olckers | Riaan | 4 +4 | 0 | 02/04/2004 |
| Oliver | Matt | 7 +5 | 10 | 26/10/2003 |
| Olivier | Wynand | 37 +5 | 50 | 18/05/2019 |
| Olmstead | Evan | 20 +10 | 10 | 18/05/2019 |
| Olowofela | Jordan | 18 +9 | 15 | 30/08/2020 |
| Olowofela | Ryan | 3 | 5 | 08/09/2020 |
| Olsen | Marcus | 9 +4 | 20 | 01/05/1999 |
| Olver | Adrian | 57 +32 | 30 | 21/11/2003 |
| Olver | Sam | 2 +9 | 10 | 24/03/2018 |
| Ongaro | Fabio | 30 +13 | 5 | 29/05/2010 |
| Onojaife | Devante | 0 +2 | 0 | 16/02/2020 |
| Onojaife | Jordan | 0 +2 | 0 | 25/11/2016 |
| Oosthuizen | Coenie | 12 +6 | 5 | 13/09/2020 |
| Orlandi | Juan Pablo | 4 +13 | 0 | 09/05/2015 |
| Ormsby | Kris | 20 +6 | 20 | 07/01/2011 |
| Orr | Cameron | 0 +9 | 0 | 17/02/2018 |
| Orr | Harrison | 0 | 0 | 00/00/0000 |
| Osman | Nick | 0 +2 | 2 | 11/02/1998 |
| Ostrikov | Andrei | 64 +34 | 15 | 02/03/2019 |
| Otuvaka | Soa | 1 +7 | 0 | 01/02/2003 |
| Oulton | Jack | 0 | 0 | 00/00/0000 |
| Ovens | Josh | 4 +18 | 0 | 01/12/2012 |
| Ovens | Laurence | 3 +14 | 0 | 23/04/2010 |
| Overend | James | 13 +5 | 15 | 23/09/2000 |
| Owen | Gareth | 15 +5 | 10 | 12/04/2019 |
| Owen | Kai | 0 +4 | 0 | 09/09/2020 |
| Owen | Michael | 12 +4 | 5 | 04/10/2009 |
| Owen | Will | 0 | 0 | 00/00/0000 |
| Owlett | Jack | 0 +5 | 0 | 05/09/2020 |
| Ozdemir | Altan | 8 +6 | 0 | 16/05/1999 |