Tenis O ile başlayan oyuncular
- Ornella De Fazio
- Olga Parres Azcoitia
- Odessa Eisch
- Oliver Anderson
- Ounmuang/Ruamrak
- Obrad Markovski
- Ornella De Fazio/Natalia Sarandi
- Otegui/Sanchez Jover
- Oliver Bonding
- Oliver Moises Aguilar Gasperin/Ricardo Fernando Romero Estrada
- Oskari Eerola
- Okuwaki/Ounmuang
- Oana Gavrila/Kathleen Kanev
- Osuigwe/Osuigwe
- Oskar Jansson
- Orlando Luz/Fernando Romboli
- Ogno/Smolenova
- Oscar Jose Gutierrez/Gabriel Roveri Sidney
- Ozan Avanoglu
- Oscar Jose Gutierrez/Juan Pablo Paz
- Ognjen Milic
- Oleksandr Ovcharenko/Davide Spina
- Oksana Kalashnikova/Kimberley Zimmermann
- Orlando Luz/Petros Tsitsipas
- Oana Gavrila/Gabriela Vilar
- Ozeki/Higashitani
- Okutoyi/Refaat
- Oksana Kalashnikova/Aliaksandra Sasnovich
- Oceane Dodin/Tatjana Maria
- Ouakaa/Hamza Reguig
- Oksana Kalashnikova/Yana Sizikova
- Ouakaa/Elsayed
- Ondrej Horak/Stepan Pecak
- Oliver Okonkwo
- Olivia Bergler/Mariia Masiianskaia
- Omar Ahmed/Saud Alhogbani
- Ozan Baris
- Oriana Gniewkowska/Ada Piestrzynska
- Oleksii Krutykh/Fryderyk Lechno Wasiutynski
- Oriol Roca Batalla/Nikolas Sanchez Izquierdo
- Ondrej Horak/Vit Kalina
- Olga Danilova/Valeriia Krokhotina
- Oeste SP
- Otakar Ungerman
- Oliver Clark Anderson/Daniel Vishnick
- Othman Bezzaz/Amine Jamji
- Oriana Gniewkowska/Marina Lubsheva
- Otakar Ungerman/Martin Van Der Meerschen
- Örebro SK (W)
- Oakland Soul SC (W)
- Olaszország
- Olivia Nicholls/Diane Parry
- Olaf Pieczkowski/Filip Pieczonka
- Olga Danilova/Iva Rafailovic
- Olivia Center/Kate Fakih
- Olimpija Ljubljana
- Oliver Crawford/Kyle Edmund
- Onyu Choi/Erica Kanna Hagi
- Overbeck/Sonesson Lidholt
- Olivia Gadecki/Elixane Lechemia
- Ozan Avanoglu/Ivan Fomin
- Ordabasy Shymkent
- Orlando Pirates
- Odense BK
- Oluwadare/Slama
- Ondrej Horak/Jan Jermar
- Obradovic/Senic
- Omar Knani/Alaa Trifi
- Olga Danilova/Jimar Geraldine Gerald Gonzalez
- Once Deportivo De Ahuachapan
- Österlen FF
- Oskar Antinheimo
- Oskar Antinheimo/Roni Mikael Hietaranta
- Olivia Bergler/Daria Gorska