O
- (Sagbama) Osiama
- (Nembe) Oroweiama
- (Brass) Oruokolo
- (Kolokuma/Opokuma) Orubiri
- (Ekeremor) Orobiri
- (Yenegoa) Opu Yenizue
- (Ogbia) Opu Kolo
- (Southern Ijaw) Opuadana
- (Ogbia) Opu Emeya
- (Yenegoa) Opuama
- (Southern Ijaw) Oporogbene
- (Ogbia) Opomatobo
- (Yenegoa) Opolo
- (Southern Ijaw) Onyoma
- (Yenegoa) Onura
- (Nembe) Onunama
- (Nembe) Oni
- (Sagbama) Ongozigbene
- (Southern Ijaw) Ondewari
- (Southern Ijaw) Olugbogbene
- (Southern Ijaw) Olugbogbene
- (Southern Ijaw) Olugbobiri
- (Southern Ijaw) Olugboboro
- (Brass) Oluassiri
- (Ogbia) Oloibiri
- (Nembe) Ologoama
- (Ogbia) Ologanga
- (Southern Ijaw) Olodi
- (Kolokuma/Opokuma) Oloibiri
- (Southern Ijaw) Olobia