| KEY | |
| OFF APP | Appearances in official national or European competitions |
| OFF GLS | Goals in official national or European competitions |
| UNO APP | Appearances in local or unofficial national competitions |
| UNO GLS | Goals in local or unofficial national competitions |
| PLAYER | PERIOD | POS | OFF APP | OFF GLS | UNO APP | UNO GLS | TOTAL APP | TOTAL GLS |
|---|---|---|---|---|---|---|---|---|
| O’BRIEN, Billy | 2017 | GK | 20 | 0 | – | – | 20 | 0 |
| O’BRIEN, Burton | 1996-1999 | MID | 28 | 1 | 1 | 0 | 29 | 1 |
| O’DONNELL, Paddy | 1986-1987 | RB | – | – | 1 | 0 | 1 | 0 |
| O’DONNELL, Stephen | 2006-2010 | MID | 52 | 6 | 1 | 0 | 53 | 6 |
| O’HAGAN, Willie | 1911-1921 | GK | 205 | 0 | 2 | 0 | 207 | 0 |
| O’KEEFE, Connor | 2016-2018 | RW | 7 | 0 | – | – | 7 | 0 |
| O’NEILL, George | 1972-1973 | WH | 6 | 0 | – | – | 6 | 0 |
| O’NEILL, John | 2003-2005 | AM | 70 | 15 | 1 | 0 | 71 | 15 |
| OBIKA, Jonathan | 2019-2021 | MID | 79 | 20 | – | – | 79 | 20 |
| OFFORD, Kieran | 2021-2023 | FW | 14 | 0 | – | – | 14 | 0 |
| OKORIE, Kelechie | 1994 | MID | 2 | 0 | – | – | 2 | 0 |
| OLUSANYA, Toyosi | 2022-2025 | FW | 84 | 19 | – | – | 84 | 19 |
| ORMOND, Hugh | 1948-1950 | FW | 3 | 0 | 1 | 0 | 4 | 0 |
| ORR, J | 1877-1881 | FB | – | – | 4 | 0 | 4 | 0 |
| ORR, Neil | 1993-1995 | CB | 36 | 1 | – | – | 36 | 1 |
| ORR, Ronald | 1898-1901 | FW | 85 | 40 | 8 | 4 | 93 | 44 |
| ORROCK, Robert | 1917-1919 | FB | 42 | 0 | – | – | 42 | 0 |
| ORSI , Kalvin | 2016-2017 | CF | 1 | 0 | – | – | 1 | 0 |
| OSBORNE, Brian | 1970-1973 | CH | 19 | 1 | – | – | 19 | 1 |
| OSBORNE, John | 1941-1942 | HB | – | – | 2 | 0 | 2 | 0 |
| OSBOURNE, Isaac | 2014-2015 | MID | 18 | 0 | – | – | 18 | 0 |
| OSENI, Owen | 2025 | FW | 11 | 0 | – | – | 11 | 0 |
| OWEN, ? | 1898-1899 | RW | 3 | 0 | – | – | 3 | 0 |
