alphabetical list:
| Dawson O'BRIEN |  | Chol-Su O |  | Sang-Sik O | |
| Satoshi OBARA |  | Tadashi OBARA | | Yuuga OBARA | |
| Sora OBATA | | Dmitrij OBATUROV |  | Christian OBERBICHLER |  |
| Hans-Peter OBERHUBER |  | Daniil OBUKHOV |  | Dmitrij OBUSJNOJ | |
| Kazunori OCHI | | Sadayoshi OCHIAI | | Alexander OCHOWICZ |  |
| Takuro ODA | | Tomoki ODA | | Aleksandr ODEGOV |  |
| Gabriel ODOR |  | Jeroen OEBEN |  | Harald OEHME | |
| Berend OENEMA | | Johan OERLEMANS | | Hans OFFRINGA | |
| Gaweł OFICJALSKI |  | Hirobumi OGASAWARA | | Yasuki OGASAWARA | |
| Yuuta OGASAWARA | | Yuuya OGATA | | Arata OGAWA | |
| Shouya OGAWA | | Takuro OGAWA | | Teruyuki OGAWA | |
| Toshiyuki OGAWA | | Jevgenij OGIBALOV | | Konstantin OGIBALOV | |
| Suguru OGIHARA | | Gavin OGILVIE | | Tatsuya OGINO | |
| Fumihiko OGIWARA | | Noriyuki OGIWARA | | Dmitrij OGLOBLIN | |
| Yuusuke OGUCHI | | Ivan OGURTSOV | | Jarosław OGÓREK | |
| Han-Seok OH |  | Hong-Jin OH | | Hyeon-Min OH | |
| Hyeon-Woo OH | | Je-Ho OH | | Jeong-Seok OH | |
| Joon-Oh OH | | Sang-Hoon OH | | Seung-Kwan OH | |
| Yong-Seok OH | | Yoon-Seong OH | | Gabriel OHNMACHT |  |
| Kristian OHR |  | Torstein OHR | | Kazuya OIKAWA | |
| Shinobu OIKAWA | | Sho OIKAWA | | Yuutaro OIKAWA | |
| Yuuya OIKAWA | | Tsuki OJIMA | | Daiki OKABE | |
| Yuuki OKABE | | Itsuki OKADA | | Kakeru OKADA | |
| Ryo OKADA | | Hiroshi OKAHISA | | Gen OKAMOTO | |
| Taishin OKAZAKI | | Aleksandr OKHOTIN | | David OKONIEWSKI | |
| Haruki OKONOGI | | Kazuhiro OKUAKI | | Chikao OKUHARA | |
| Tsunaki OKUHARA | | Kazuki OKUMURA | | Tatsuya OKUMURA | |
| Yuuki OKUMURA | | Tsimafei OKUNEU |  | Sergej OKUNEV | |
| Igor OKUNJOV | | Yui OKUNO | | Daiki OKUYAMA | |
| John Arthur OLAFSEN | | Martin Emil OLAUSSEN | | Ruben OLDENBURGER | |
| Peter OLDENHOF | | Remco OLDE HEUVEL | | Wouter OLDE HEUVEL | |
| Aleksej OLEJNIK | | Andrej OLEJNIKOV | | Vladislav OLENIN | |
| Mikhail OLENJOV | | Jegor OLESKO | | Ryan OLIJNYK | |
| Isaiah OLIVER | | Niels OLIVIER | | Samuli OLLANKETO |  |
| Jakob OLLICK | | Johnny OLOF | | Mattias OLOFSSON |  |
| Rune OLSEN-FARSTAD | | Martin Stoltz OLSEN | | Willy OLSEN | |
| Craig OLSON | | Darren OLSON | | Kirk OLSON | |
| Paul OLSON | | Christian OLSSON | | Joel OLSÉN | |
| Tom OLTHOF | | Joery OLTHUIS | | Björn OLTMER | |
| Thorsten OLTMER | | Alexander OLTROP | | Zjaslan OLZJABAJEV | |
| Zei-Son OM | | Jegor OMELTSJENKO | | Hitoshi ONDA | |
| Kouichi ONO | | Ryousuke ONO | | Shouta ONO | |
| Suguru ONO | | Yasuyuki ONO | | Masaaki ONODERA | |
| Shunichi ONODERA | | Subaru ONODERA | | Kenjiro ONODZUKA | |
| Koujiro ONODZUKA | | Keigo ONOZATO | | Kouki OOBA | |
| Masaki OOBA | | Kou OOBAYASHI | | Masahito OOBAYASHI | |
| Takahiro OOE | | Takehiro OOE | | Tomoki OOFUJI | |
| Ryo OOGAKI | | Hiroyuki OOHASHI | | Tomomi OOHASHI | |
| Kouji OOHIRA | | Akira OOI | | Takenori OOI | |
| Mark OOIJEVAAR | | Akihiko OOISHI | | Takuya OOISHI | |
| Ryuutaro OOIZUMI | | Satoshi OOKE | | Kazumitsu OOKUBO | |
| Yuuta OOKUBO | | Yuutaro OOKUMA | | Naokazu OOKURA | |
| Johannes OOMEN | | Ryuuichi OOMICHI | | Ryuunosuke OOMICHI | |
| Yasuhiro OOMICHI | | Hiroshi OOMIYA | | Eiji OOMORI | |
| Fuyuki OOMORI | | Masahiko OOMURA | | Ichiro OONISHI | |
| Tomonori OONISHI | | Yuusuke OONISHI | | Yuusuke97 OONISHI | |
| Haruki OONO | | Natsu OONO | | Eiji OONUKI | |
| Bram OORT | | Bungo OOSAKA | | Kouki OOSAKI | |
| Takuya OOSAKI | | Takashi OOSATO | | Kenta OOSAWA | |
| Wataru OOSAWA | | Souki OOSHIMA | | Takahiro OOSHIMA | |
| Tatsuki OOSHIMA | | Kouki OOSHUU | | Renki OOSHUU | |
| Jorrit OOSTEN | | Roderick OOSTEN | | Gert-Jan OOSTERBOS | |
| Dirk OOSTERINK | | Fred OOSTERLAAN | | Akio OOTA | |
| Ayato OOTA | | Masahito OOTA | | Masakiyo OOTA | |
| Akito OOTAKE | | Takuzo OOTAKE | | Hitoshi OOTANAKA | |
| Yushi OOTANAKA | | Stefan OOTES | | Daisuke OOTOUGE | |
| Seitaro OOTOUGE | | Takanori OOTSU | | Tatsuki OOTSUKA | |
| Amon OOTSUKI | | Riku OOTSUKI | | Takahiro OOTSUKI | |
| Yuuta OOTSUKI | | Takuma OOUCHI | | Tomonori OOUCHI | |
| Kouji OOWADA | | Makoto OOWADA | | Tsukasa OOWADA | |
| Kousuke OOYANAGI | | Denis OPALEV | | Artur OPALIŃSKI | |
| Ivan OPARIN | | Ion OPINCARIU |  | Alexandru Vlad OPREA | |
| Sebastiaan ORANJE | | Eemil-Oskar ORAS | | Jeroen OREMUS | |
| Roman ORESJIN | | Aleksandr ORESJKIN | | Bat-Erdene ORGIL |  |
| Jacques ORIE | | Kenshin ORIKASA | | Norio ORIKAWA | |
| Yuushin ORITA | | John ORLIKOW | | Kelly ORLOFF | |
| Boris ORLOV | | Jurij ORLOV | | Mikhail ORLOV | |
| Oleg ORLOV | | Sergej ORLOV | | Vladimir ORLOV | |
| Eric ORLOWSKY | | João Francisco ORNELAS DE JESUS |  | Khyl ORSER | |
| Liam ORTEGA | | Kaito OSADA | | Manabu OSADA | |
| Tsubasa OSADA | | Nikita OSADTSJIJ | | Takafumi OSAME | |
| Shintaro OSANAI | | Toshiyuki OSANO | | Rasjid OSIN | |
| Wierd OSINGA | | Dmitrij OSIPENKO | | Aart OSKAM | |
| Hidetoshi OSODA | | Oleg OSOKIN | | Michał OSTASZEWSKI | |
| Aleksandr OSTROVSKIJ | | Vjatsjeslav OSTROVSKIJ | | Paweł OSTROWSKI | |
| Shunya OTANI | | Gabriel OTHENIN-GIRARD | | Steffen Floor OTNÆS | |
| Yoshimi OTSUKI | | Niels OTT | | Tom-Benedikt OTT | |
| Bas OTTEN | | Ivar OTTENBROS | | Kai-Arne OTTENHOFF | |
| Arjan OTTENS | | Coen OTTERSPEER | | Hein OTTERSPEER | |
| Muncef OUARDI | | Job OUDE VRIELINK | | Tim OUDE WOLCHERINK | |
| Simon OUDSHOORN | | Ton OUDSHOORN | | Vincent OUDSHOORN | |
| John OUDT | | Alphonse OUIMETTE | | Mitch OUT | |
| Steven OUTEN |  | Aleksandr OVDIN | | Ad OVERDEVEST | |
| Arjan OVERDEVEST | | Thomas OVEREND | | Jeremy OVERHEUL | |
| Rickardo OVERHEUL | | Kevin OVERLAND | | Jelle OVERMARS | |
| Pieter OVERMARS | | Jay OVERVLIET | | Niels OVERVOORDE | |
| Leif Marius OVLI | | Aleksandr OVRAZJKO | | Sergej OVSJANNIKOV | |
| Aleksandr OVTSJARENKO | | Aleksandr OVTSJINNIKOV | | Maksim OVTSJINNIKOV | |
| Mateusz OWCZAREK | | Christian OWESEN | | Tom Erik OXHOLM | |
| Kouki OYAMA | | Mikio OYAMA | | Shousuke OYAMA | |
| Haruki OZAWA | | Nao OZAWA | | Ryuuichi OZAWA | |
| Igor OZEROV | |
