O
- (Brass) Otokolo-Kiri
- (Brass) Obi
- (Nembe) Osua
- (Brass) Obetekiri
- (Brass) Otekekiri
- (Brass) Okoribuko
- (Brass) Olukugbene
- (Brass) Okobotuo
- (Brass) Obudogbene
- (Brass) Oruwo
- (Brass) Otolo
- (Brass) Opuaba
- (Brass) Onunupele
- (Brass) Opoloicheli
- (Brass) Omonikiri
- (Brass) Odufie
- (Southern Ijaw) Ozezebiri
- (Kolokuma/Opokuma) Oyebu
- (Southern Ijaw) Oyeregbene
- (Yenegoa) Oweikorogba
- (Ogbia) Outar
- (Ogbia) Otuokpot
- (Ogbia) Otuogori
- (Brass) Otumakiri
- (Ogbia) Otuasiga
- (Southern Ijaw) Otuan
- (Ogbia) Otuaka
- (Brass) Otokolopiri
- (Nembe) Otatubu
- (Southern Ijaw) Osokoma