Wales
O
- Oakdale, Wales
- Oakeley Square
- Oakenholt
- Oakfield, Torfaen
- Oakford
- Oaklands, Powys
- Oakley Park
- Oakwood, Neath Port Talbot
- Ochr glan hafon
- Ochr-y-foel
- Ochrwyth
- Ogmore
- Ogmore Vale
- Ogmore-by-Sea
- Olchfa
- Old Bishton
- Old Church Stoke
- Old Colwyn
- Old Cwmbran
- Old Furnace, Torfaen
- Old Goginan
- Old Pentre
- Old Radnor
- Old Rhosrobin
- Old Sontley
- Old Treowen
- Old Warren, Wales
- Oldcastle, Wales
- Oldcastle, Monmouthshire
- Oldhall
- Oldwalls
- Oldway, Wales
- Olmarch
- Onen
- Onen, Tair
- Onllwyn
- Orange Gardens
- Orlandon
- Ormes Head, Little
- Orsedd
- Osbaston, Wales
- Over Monnow
- Overleigh, Wales
- Overton, Swansea
- Overton, Wrexham
- Owlbury
- Owrtyn
- Oxwich
- Oxwich Green
- Oystermouth and Brynau