From Trewornan, Cornwall to all cities in Nottinghamshire starting with letter O
- Old Basford, Cornwall
- Old Lenton, Cornwall
- Oldcotes, Cornwall
- Ollerton, Cornwall
- Ompton, Cornwall
- Ordsall, Cornwall
- Orston, Cornwall
- Osberton, Cornwall
- Ossington, Cornwall
- Owthorpe, Cornwall
- Oxton, Cornwall