Irlanda
Países do mundo
O
- (South Dublin) Oldbawn
- (County Galway) Oranmore
- Oileán Ciarraí
- (Kildare) Old Kilcullen
- (Meath) Oldcastle
- (Kildare) Oughterard
- (County Galway) Oughterard
- (Louth) Omeath
- (Fingal County) Oldtown
- (Limerick City and County Council) Old Kildimo
- (Clare) O’Briensbridge
- (Wexford) Oilgate
- (Limerick City and County Council) Oola
- (Wexford) Oulart
- (County Monaghan) Oram
- (County Leitrim) Orcusconny
- (Sligo) Ogham
- (Sligo) Oldrock
- (Sligo) Oghambaun
- (Wicklow) Oghi Upper
- (Wicklow) Oghil Lower
- (Mayo County) Oxford
- (Mayo County) Owenduff
- (County Galway) Ower
- (County Galway) Owenbristy
- (Clare) Oughtmama
- (An Cabhán) Oggal
- (County Leitrim) Oghill Cross Roads
- (Sligo) Owenbeg