- Olivarez Number 7 Colonia
- Olivarez Number 8 Colonia
- Olivarez Number 9 Colonia
- Olivia
- Olivia Lopez de Gutierrez Colonia
- Ollie
- Olmito
- Olmito and Olmito Number 2 Colonia
- Olmos
- Olmos
- Olmos
- Olmos Park
- Olney
- Olton
- Olympic Colonia
- Omaha
- Omen
- Onalaska
- One River Place Colonia
- Onion Creek
- Onion Creek
- Onion Creek (historical)
- Onion Spring
- Opdyke
- Opdyke West
- Opelika
- Oplin
- Ora
- Oran
- Orange