O
- (Cibola County) Ojo Caliente
- (Conecuh County) Omlee
- (Cleburne County) Old Town
- (Campbell County) Orange
- (Colbert County) Ocate
- (Cibola County) Orchard Place
- (Clarke County) Oil Center
- (Clay County) Oscura
- (Ashley County) Omega
- (Colbert County) Optimo
- (Dallas County) Onava
- (DeKalb County) Otowi
- (Fayette County) Otto
- (Covington County) Ojo Sarco
- (Colbert County) Ojo Feliz
- (Coosa County) Obar
- (Conecuh County) Old Wright Place
- (Cullman County) O'Neil Landing
- (Chambers County) Oak Grove
- (Clarke County) Ochoa
- (Dallas County) Ojita
- (Covington County) Ojito
- (Etowah County) Ojito
- (Dallas County) Ojitos Frios
- (Etowah County) Ojo Caliente
- (Coffee County) Ojo Encino
- (Ashley County) Old Campbell Place
- (Escambia County) Old Carthage
- (Arkansas County) Old Chilili
- (Chambers County) Old Hachita