- Onwubiko Agozino
- Onyango Oloo
- Onyeka Obasi
- Onyekachi Wambu
- Open letter to the Commissioner of Police
- Open Society Foundation
- Open Society Foundations
- OPEN SOCIETY INITIATIVE FOR WEST AFRICA (OSIWA)
- Open Society Institute for West Africa
- Open Society Justice Initiative
- Opera Mundi
- OperaMundi | BdF
- OperaMundi | Brasil de Fato
- Ophélie Latil et Aurélie Chatelard
- Organisation mondiale contre la torture
- Organizações Moçambicanas da Sociedade Civil | @Verdade
- Orlando Castro
- Orlando Patterson
- Oru Ntui
- Orwa Michael
- Osai Justina Ojigho
- Osai Ojigho
- Osarhieme George
- Osaze Lanre Nosaze
- Oscar D. Simela
- Oscar Fortin
- Oscar H. Blayton
- Oscar Ramjeet
- OSI Angola, AJPD
- Osita Ebiem