- Olive Green
- Olivesburg
- Olivett
- Ollins Corners
- Olmsted
- Olmsted Falls
- Olmsted Trailer Park
- Olszeski Town
- Olwine Mobile Home Park
- Omar
- Omega
- Oneida
- Oneida
- Ontario
- Opperman
- Oran
- Orange
- Orange
- Orange
- Orange Center
- Orangeville
- Orbiston
- Orchard Acres
- Orchard Beach
- Orchard Island
- Orchard Lane Trailer Court
- Orchard Mobile Home Park
- Orchard View
- Oregon
- Oregon Corners