| VFL/AFL | AFLW | |||
VFL/AFL
| Player | MFC games | MFC goals | Years | |
| Darren O'Brien | 24 | 9 | 1996-1997 | |
| Paul O'Brien | 22 | 0 | 1980-1983 | |
| Tom O'Brien | 4 | 0 | 1926 | |
| Andrew Obst | 149 | 60 | 1990-1997 | |
| Joe O'Carroll | 3 | 2 | 1920 | |
| Frank O'Connor | 24 | 29 | 1947-1948 | |
| Hughie Odgers | 59 | 2 | 1909-1912, 1920 | |
| Kelly O'Donnell | 80 | 67 | 1979-1984 | |
| Des O'Dwyer | 8 | 5 | 1978, 1981-1982 | |
| Steve O'Dwyer | 84 | 45 | 1987-1991 | |
| Gordon Ogden | 134 | 3 | 1928-1937 | |
| Terry Ogden | 3 | 0 | 1932 | |
| Alick Ogilvie | 1 | 1 | 1905 | |
| Laurie Ogilvie | 4 | 3 | 1901 | |
| Alex Ogilvy | 4 | 0 | 1921 | |
| Jack O'Keefe | 46 | 27 | 1939-1942 | |
| Peter O'Keefe | 10 | 1 | 1976-1979 | |
| George O'Keeffe | 13 | 1 | 1951-1952 | |
| Alf Oldham | 3 | 2 | 1922 | |
| Clayton Oliver | 205 | 58 | 2016-2025 | |
| George Oliver | 1 | 0 | 1909 | |
| Basil Onyons | 37 | 32 | 1905-1908 | |
| Jim Oppy | 3 | 0 | 1945 | |
| Trent Ormond-Allen | 8 | 1 | 1995-1996 | |
| Ernie O'Rourke | 39 | 46 | 1945-1948 | |
| Max Orr | 7 | 4 | 1952-1953 | |
| Graham Osborne | 146 | 61 | 1966-1977 | |
| Ken Osborne | 13 | 7 | 1966-1968 | |
| Michael O'Sullivan | 53 | 11 | 1982-1986 | |
| Con O'Toole | 4 | 0 | 1950 | |
| Luke Ottens | 4 | 0 | 1999 | |
| Barry Ough | 1 | 0 | 1975 | |
| Rod Owen | 9 | 19 | 1991 | |
| Mal Owens | 16 | 3 | 1973-1975 | |
AFLW
| Player | MFC games | MFC goals | Years | Also played for |
| Elise O'Dea | 28 | 6 | 2017-2020 | Carlton |
| Molly O'Hehir | * | * | 2025- | |