Where completed, the blue button links to their player profile. For full player details refer to the Paul Joannou book "The Ultimate Who's Who" and it's supplement.
| Name | P | Jnd | Dep | App | Sub | Gls | |
| Oates G | 1976 | 1978 | 33 | 10 | 3 | ||
| Obertan G | OR | 2011 | 2016 | 48 | 29 | 3 | |
| O'Brien A | OL | 2001 | 2007 | 1 | 8 | 0 | |
| O'Brien A | CH | 2001 | 2005 | 157 | 15 | 7 | |
| O'Brien P | RB | 1894 | 1895 | 12 | 2 | ||
| O'Brien L | M | 1988 | 1994 | 161 | 24 | 22 | |
| O'Neil L | IL | 1961 | 1965 | 1 | 0 | ||
| O'Neil T | RB | 1942 | 1948 | 1 | 0 | ||
| O'Neill M | F | 1987 | 1989 | 43 | 15 | 17 | |
| Onyewu 0 | CH | 2007 | 2007 | 7 | 4 | 0 | |
| Orr R | IF | 1901 | 1908 | 180 | 70 | ||
| Osbourne F | IF | 1940 | 1940 | 1 | 0 | ||
| Ostler J | CH | 1896 | 1900 | 78 | 2 | ||
| Owen M | F | 2005 | 2009 | 65 | 14 | 30 | |
| Owens M | LB | 1973 | 1977 | 1 | 0 | 0 |
