Football referees
Ousmane Diakate
Onur Can Dolğun
Oliver Drachta
Ole-Alexander Ekeli Valen
Ozan Ergün
Oleg Evstigneev
Olsid Ferataj
Oliver Fix
Oliver Fluch
Oscar Forsberg
Omar Gallo
Oleksii Garkusha
Ondřej Ginzel
Oğuzhan Gökçen
O. Goldrick
Oscar Javier Gómez Flórez
Orel Grinfeeld
Onur Güneş
Oleg Gurchenko
Oleg Gusakov
Oleksii Harkusha
Ovidiu Alin Hațegan
Oleg Igorevich Zhuravlev
Osama Ismail
O. Jantunen
Oh-Hyeon Jeong
Oscar Johnson
Oleksandr Kalyonov
Orhan Karaboğa
Okan Kayataş
Ola Kellerhals
Omar Khaild
Oleg Kogut
Osman Köksaldı
Oleg Koretskiy
Osiase William Koto
Oleksandr Kovalenko
Orlando Kuka
O. Kwinda
Oskar Lämpel
Oliver Langford
Owen Lawrence
Ondřej Lerch
Omri Levi
Oliver Lossius
Oliver Mackey
Óscar Maldonado Urey
Óscar Mejía García
Othusitse Modise
Osman Mohammadi