- Oadby
- Oakengates
- Oakham
- Oakhanger
- Oakhill
- Oakington
- Oakley
- Oakley
- Oakley
- Oaksey
- Oare
- Oban
- Occold
- Ochiltree
- Ockley
- Odcombe
- Odiham
- Offham
- Offwell
- Ogmore Vale
- Ogmore-by-Sea
- Okehampton
- Old Basing
- Old Bolingbroke
- Old Buckenham
- Old Dalby
- Old Harlow
- Old Kilpatrick
- Old Leake
- Old Newton
- Old Sarum
- Old Windsor
- Oldbury
- Oldbury-on-Severn
- Oldham
- Oldmeldrum
- Olney
- Olveston
- Omagh
- Ombersley
- Orcheston
- Orford
- Orkney
- Orleton
- Orlingbury
- Ormesby St Margaret
- Ormiston
- Ormskirk
- Orpington
- Orsett
- Orston
- Orton
- Orwell
- Osbournby
- Osmington
- Osmotherley
- Ossett
- Oswaldkirk
- Oswestry
- Otford
- Othery
- Otley
- Otley
- Otterburn
- Ottershaw
- Otterton
- Ottery St Mary
- Ottringham
- Oughtibridge
- Oundle
- Outwell
- Over
- Over
- Over Kellet
- Over Wallop
- Overcombe
- Overstrand
- Overton
- Overton
- Overton
- Overtown
- Oving
- Owermoigne
- Owslebury
- Owston Ferry
- Oxenhope
- Oxford
- Oxhill
- Oxted
- Oxton
