- OCP
- Oded Berman
- Oded Netzer
- OFMD
- Ogechi (Vivian) Nwadiaru
- Oguz Gencay
- Oguzhan Alagoz
- Ohad Eisenhandler
- Ohio State University Student Chapter
- Okan Arslan
- Oklahoma State University Student Chapter
- Ola Batarseh
- Ola Jabali
- Olaf Jahn
- Oleg A. Prokopyev
- Oleg Gusikhin
- Oleksandr Akulov
- Olga Bagatourova
- Olga Raskina
- Olivia Natan
