Poids Mi-Moyens Hommes
 | Noah Lindsey | 0-1-0 REC | #6641 |  |
 | Nordine Taleb | 7-5-0 UFC | #853 |  |
 | Oban Elliott | 3-2-0 UFC | #1109 |  |
 | Oganes Voskanyan | 1-1-0 REC | #2001 |  |
 | Oleg Dadonov | 0-1-0 REC | #5491 | |
 | Oliver Enkamp | 0-2-0 UFC | #3430 |  |
 | Olivier Fleurmon | #7498 | | |
 | Olli Santalahti | 2-3-0 REC | #3041 |  |
 | Omar El Dafrawy | 4-1-0 REC | #1305 |  |
 | Omar Hussein | 0-2-0 REC | #3467 |  |
 | Omar Santana | 0-1-0 REC | #6970 |  |
 | Omari Akhmedov | 9-5-1 UFC | #549 | |
 | Omoyele Gonzalez | 0-1-0 REC | #5310 | |
 | Omran Chaaban | 2-0-0 REC | #4036 | |
 | Orion Cosce | 1-2-0 UFC | #3679 | |
 | Orlando Sanders | 0-1-0 REC | #6959 | |
 | Orlando Wiet | 1-1-0 UFC | #3059 | |
 | Oseyiomon Oiyemhonlan | 1-2-0 REC | #4261 | |
 | Oskar Staszczak | 1-0-0 REC | #1624 |  |
 | Oskar Szczepaniak | 4-2-0 REC | #2594 | |