Athletes · O
- Oana Amalia Marinescu
- Oana Antoaneta Belea
- Oana Maria Purcaru
- Obencio Espinoza
- Obenrocksman Arrah
- Oceane Perree
- Octavin Jackson
- Odett Bernath
- Odilon Batista
- Oguzhan Kalyoncu
- Okamura Muneaki
- Oksana Bryhidyr
- Oksana Grishina
- Oksana Kaliuzhna
- Oksana Kulpa
- Oksana Lubeinik
- Oksana Piari
- Ole Kristian Vaga
- Oleg Emelianov
- Oleg Zhur
- Oleh Kryvyi
- Oleksandr Bohdanov
- Oleksandr Mincha
- Oleksandr Morozow
- Oleksandra Khovcyeh
- Oleksandra Khovrych
- Oleksandra Khvorych
- Olena Hlazun
- Olena Kushnirova
- Olena Mykhailiuk
- Olena Okanovic
- Olesya Kochura
- Olesya Sun
- Olga Beliakova
- Olga Campos Arroyo
- Olga Kolaeva
- Olga Novikova
- Olga Paolina Gloria Bonifaz
- Oliver Adzievski
- Oliver Prochazka
- Olivia Bian
- Olivia Oneid
- Olivia Pohankova Kovac
- Olivier Kremers
- Oliwia Dobrowolska
- Olushomo Oni
- Oluwatobi Ishola
- Omar Bautista
- Omar Boresli
- Omar Deckard
- Omar Khaldi
- Omar Naser Alden
- Omar Suleiman
- Omella Anguen
- Omer Bahamed
- Ommie Ali
- Ommie Ryan
- Onder Adsay
- Ondrej Kmostak
- Ontario Alexander
- Opekinova Ekaterina
- Oriana Ailen Canelo
- Orlandina Balan
- Orlando Perdomo Lopez
- Ornella Angileri
- Ornella Angiueri
- Ornella Turturro
- Ornella Victoria Turturro
- Orsolya Trucza
- Orville Burke
- Oscar Antonio Zaracho Sanchez
- Oscar Sanchez
- Oscar Young
- Oshanda Rhoden
- Osiris M. Trumpe
- Osiris Trumpe
- Oskar Tchorzewski
- Osmar Alanis
- Ossama Ashour
- Oswaldo Gonzalez
- Oswaljhans Gonzalez
- Othmane Mouhssin
- Otis Hooper
- Ottavia Mazza
- Oussah Dith
- Ovidijus Ringys
- Oyku Basar
- Oyungerel Bayarsaikhan