Poids Mi-Moyens Hommes
 | Omoyele Gonzalez | 0-1-0 REC | #6042 |  |
 | Omran Chaaban | 3-0-0 REC | #1271 |  |
 | Orion Cosce | 1-2-0 UFC | #3911 | |
 | Orlando Sanders | 1-1-0 REC | #587 | |
 | Orlando Wiet | 1-1-0 UFC | #3134 |  |
 | Oseyiomon Oiyemhonlan | 1-2-0 REC | #4837 | |
 | Oskar Staszczak | 1-0-0 REC | #2583 |  |
 | Oskar Szczepaniak | 4-2-0 REC | #3005 | |
 | Osvaldo Benedito | 0-1-0 REC | #5190 |  |
 | Oton Jasse | 0-3-0 REC | #4394 |  |
 | Oualy Tandia | 1-0-0 REC | #899 | |
 | Ousmane Camara | 1-0-0 REC | #1525 | |
 | Ovidio Bojorquez | 0-1-0 REC | #7126 |  |
 | Ozzy Martin | #8170 |  | |
 | Paddy Wilkinson | 0-1-0 REC | #6423 |  |
 | Papy Abedi | 1-3-0 UFC | #3748 |  |
 | Pascal Krauss | 2-2-0 UFC | #3457 |  |
 | Pat Miletich | 8-2-0 UFC | #352 | |
 | Pat Pytlik | 0-1-0 REC | #6597 |  |
 | Patrice Evra | #3073 | |