People who have competed at Australian events. Australia only, for now.
| Otávio Serafim | Black | Grappling Bros / GFTeam |
| Otis Antreou | Blue | Peninsula MMA |
| Otis Craven | White | DKMMA |
| Otis Hobin | White | Pacheco Jiu Jitsu |
| Otis Kain | White | Coringa Jiu-Jitsu |
| Otis Millard Jorda | Blue | Ice Cold Jiu-Jitsu |
| Otis Rhone | White | Ortiz Martial Arts Academy |
| Otto Christie | Grey | Vangarde BJJ |
| Otto Flach Dos Santos | White | GRACIE BARRA CARINGBAH |
| Otylia Franco | Blue | SOUTHSIDE BRAZILIAN JIU-JITSU OFFICIAL |
| Owen Blakemore | White | Galeb BJJ |
| Owen Chilton | White | shindo new breed |
| Owen Croker | White | De Been 100% Jiu Jitsu |
| Owen Dealy | Grey | Perkin's Jiu Jitsu |
| Owen Kouyoumtzoglou | White | DOMINANCE |
| Owen Ly | Unknown belt | Musa Taekwondo Pty Ltd |
| Owen Smith | Orange | Australian Elite Team · Resilience Training Centre |
| Owen Tincombe | Blue | Scrappy MMA |
| Owen Whitaker | Grey | GRACIE BARRA CAMPBELLTOWN |
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