O
- O'Halloran, Joyce
- Oberhuber, Tomáš
- Ogawa, Toshiyuki
- Ogorzalek, Maciej J.
- Oh, Myoungho
- Ohara, Atsumi
- Okubo, Shigenori
- Okuda, Takashi
- Olejček, Vladimír
- Omelka, Marek
- Onwuatu, Jerry U.
- Ordokhani, Yadollah
- Orlando, Giuseppe
- Orozco, Jorge Luis
- Orsáková, Martina
- Österreicher, Ferdinand
- Osuský, Jakub
- Otáhal, Antonín
- Outbib, Rachid
- Outrata, Jiří V.
- Ozcaldiran, Kadri