Poids Légers Hommes
 | Olivier Aubin-Mercier | 7-5-0 UFC | #177 |  |
 | Omar Morales | 3-4-0 UFC | #2521 |  |
 | Omar Reguigui | 0-1-0, 1NC REC | #4583 |  |
 | Omar Tugarev | 0-2-0 REC | #4298 |  |
 | Omiel Brown | 9-3-0 REC | #390 |  |
 | Ondrej Petrasek | 1-1-0 REC | #6735 |  |
 | Orlando Wilson Prins | 2-4-0 REC | #3199 |  |
 | Oron Kahlon | 0-1-0 REC | #5520 |  |
 | Oscar Mendez | 0-1-0 REC | #5158 |  |
 | Oscar Ownsworth | 2-3-0 REC | #461 | |
 | Osman Minbatirov | 1-1-0 REC | #5902 |  |
 | Ottman Azaitar | 2-3-0 UFC | #1872 |  |
 | Owen Jason | 1-0-0 REC | #7802 |  |
 | Ozan Aslaner | 3-2-0 REC | #1092 |  |
 | Pablo David | 0-1-0 REC | #7804 | |
 | Paddy Pimblett | 8-1-0 UFC | #53 | |
 | Pat Audinwood | 0-2-0 UFC | #5583 |  |
 | Pat Healy | 0-5-0, 1NC UFC | #2963 | |
 | Pat Jones | 0-1-0 REC | #6973 |  |
 | Patrick Ocheme | 3-0-0 REC | #419 |  |