| Name | Nation |
|---|---|
| O'Brien, Kelland | AUS |
| O'Connor, Ben Alexander | AUS |
| O'Connor, Ronan | IRL |
| Obdržálek, Tomáš | CZE |
| Obholzer, Theodor | GBR |
| Obrand, Jeremy | CAN |
| Ocampo, Victor | COL |
| Ochoa, Carlos Francisco | PHI |
| Oda, Hijiri | JPN |
| Oelke, Tim | GER |
| Ogata, Takahiko | JPN |
| Oh, Jeseok | KOR |
| Oikawa, Kazusa | JPN |
| Oka, Atsushi | JPN |
| Okamika Bengoetxea, Ander | ESP |
| Okamoto, Hayato | JPN |
| Oldani, Stefano | ITA |
| Oliveira Fábio, Marcelo Pinto | POR |
| Oliveira Figueiredo, Frederico José | POR |
| Oliveira Santos Simoes, Nélson Filipe | POR |
| Oliver, Ben | NZL |
| Olivero, Simone | ITA |
| Olivo, Bryan | ITA |
| Onley, Oscar | GBR |
| Onodera, Rei | JPN |
| Oomen, Sam | NED |
| Oram, James | NZL |
| Orins, Robin | BEL |
| Örken, Ahmet | TUR |
| Ormiston, Callum | RSA |
| Orts Lloret, Felipe | ESP |
| Osko, Milosz | POL |
| Osorio Carvajal, Alejandro | COL |
| Ospina, Carlos Andres | COL |
| Oss, Daniel | ITA |
| Othman, Afiq Huznie | MAS |
| Otruba, Jakub | CZE |
| Otta, Josef | CZE |
| Ottema, Rick | NED |
| Ourselin, Paul | FRA |
| Ovett, Freddy | AUS |
| Owsian, Lukasz | POL |
| Oyarzún, Carlos Iván | CHI |
| Oyola Róbigzon, Leandro | COL |
| Özgür, Batuhan | TUR |
| Ozkalbim, Kaan | TUR |
