- Oberholzer
- Oberthur Thomas
- Obiang Ndong Grégory
- Obidzinski Krystof
- Obiero H.M.
- Obour Peter Bilson
- Occelli Martina
- Occhipinti Angelo
- Ochatt Sergio
- Ochoa M
- O'Donovan J.T.
- Oehen Bernadette
- Oehen Bernadette
- Oelofse
- Oenema Oene
- Oettli Pascal
- Offei Samuel K.
- O’grady Anthony P
- O’hara Graham
- Ohm Magdalena
- Oihabi Abdallah
- Oizumi Nobuaki
- Ojeda Jonathan Jesus
- Olbrisch Mathias
- Olivares Fábio L.
- Oliver Robert
- Oliver-Solà Jordi
- Oliver Yvette M.
- Ollivier Guillaume
- Ollivier Jean
- Olry Paul
- Oluwole Fatunbi Abiodun
- Olvera-Velona Angeluz
- Omae
- Omon Bertrand
- Onduru D.D.
- O'Neill
- O'Neill Tim
- Onofri Andrea
- Oonincx Dennis G. A. B.
- Oosterhuis Derrick M.
- Oosting Simon
- Orban Philippe
- Ordás Bernardo
- Oriol Magrans José
- Orlandi Fabio
- Orounladji Boko Michel
- Orozco-Aguilar Luis
- Orozco-Sánchez Fernando
- Orsini Francesco
- Orsini Francesco
- Ortiz-Hernandez Laura
- Ortman Tove
- Orton Thomas
- Osdaghi Ebrahim
- Oses Rómulo
- Osterholz William R.
- Oteros Jose
- Otieno Nickson Erick
- Ott Matthew A.
- Ott Salomé
- Oturan Mehmet A.
- Oturan Nihal
- Ouabbou Hassan
- Ould-Sidi
- Ow David W.
- Owen Luke
- Owens L.
- Ozier-Lafontaine Harry
- Ozier-Lafontaine Harry
- Ozier-Lafontaine H.
- Ozturk Ibrahim