Fighters — O
36 tracked fighters starting with O.
- Oban Elliott12-5-0 · Welterweight · UFC
- Océane Samson3-1-0 · Strawweight · UAEW
- Ode Osbourne13-9-0 · Flyweight · UFC
- Olaf Alfonso8-12-0 · Lightweight · TPF
- Oleg Taktarov17-5-2 · Heavyweight ·
- Oleksandr Usyk25-0-0 · heavyweight · Boxing
- Oli Thompson22-16-0 · Light Heavyweight · GOR MMA
- Oliver Enkamp11-4-0 · Welterweight · Bellator MMA
- Olivier Aubin-Mercier21-5-0 · Lightweight · PFL
- Olivier Murad7-2-0 · Featherweight · CZ
- Olivier Poisson6-1-0 · Bantamweight · SMMA
- Ollie Sarwa9-1-0 · Featherweight · CWFC
- Ollie Schmid4-3-0 · Featherweight · UFC
- Oluwale Bamgbose6-4-0 · Middleweight · UFC
- Omar Bejarano0-0-0 · Flyweight · Inka MMA
- Omar El Dafrawy16-6-0 · Welterweight · PFL
- Omar Hussein12-7-0 · Welterweight · PFL
- Omar Morales11-4-0 · Lightweight · UFC
- Omari Akhmedov24-8-1 · Light Heavyweight · PFL
- Omran Chaaban10-1-0 · Welterweight · PFL
- Onassis Parungao2-1-0 · Light Heavyweight · IAFC
- Ondřej Raška12-10-0 · Middleweight · OKMMA
- Orion Cosce8-2-0 · Middleweight · UFC
- Orlando Sanders6-3-0 · Welterweight · LFA
- Orlando Welt1-5-0 · Welterweight
- Oscar Cota11-3-0 · Heavyweight · DWCS
- Oscar Jurado Sánchez6-2-0 · Flyweight · LFA
- Oscar Ownsworth10-5-1 · Lightweight · CWFC
- Osimkhon Rakhmonov17-5-0 · Featherweight · ACA
- Oskar Piechota11-3-1 · Middleweight · UFC
- Otari Tanzilovi10-2-0 · Featherweight · UFC
- Ottman Azaitar13-3-0 · Lightweight · UFC
- Oumar Sy12-2-0 · Light Heavyweight · UFC
- Ousmane Thomas Diagne6-8-1 · Lightweight · URCC
- Ovince St. Preux27-18-0 · Light Heavyweight · UFC
- Ozzy Diaz10-4-0 · Middleweight · UFC