| Ó Méith |
Old Town |
Orchard Bridge |
| O'Brien's Bridge |
Old Town |
Oristown |
| O'Briensbridge |
Old Twopothouse Cross Roads |
Orkneys Cross Roads |
| O'Callaghansmills |
Oldbawn |
Ormond View |
| O'Connell Bridge |
Oldboleys |
Orristown Cross Roads |
| O'Neill's Cross Roads |
Oldbridge |
Oughtagh |
| Oaghley |
Oldcastle |
Oughter |
| Oakfield |
Oldcastle |
Oughterard |
| Obelisks |
Oldcastletown |
Oughterard |
| Odoca |
Oldchapel |
Oughtiv |
| Oggal |
Oldcourt |
Oughtmama |
| Oghil |
Oldcourt |
Oulart |
| Oghill Bridge |
Oldcourt |
Ouley |
| Oghill Cross Roads |
Oldcourt |
Oultort |
| Ogonnelloe |
Oldgrange |
Ourtnagapple |
| Oil Mill Bridge |
Oldleagh |
Ouvry Cross Roads |
| Oileán Ciarraí |
Oldleighlin |
Ovens |
| Oilgate |
Oldmill Bridge |
Ovenstown |
| Old Bride Bridge |
Oldstreet |
Ovoca |
| Old Bridge |
Oldtown |
Owenbeg |
| Old Chapel Cross Roads |
Oldtown |
Owenbristy |
| Old Connaught |
Oldtown |
Owenduff |
| Old Courth |
Oldtown |
Owenea Bridge |
| Old Kilcullen |
Oldtown Cross Roads |
Ower |
| Old Kildimo |
Oldtowndonore |
Owgarrif Bridge |
| Old Mountain |
Omeath |
Ownagarry Bridge |
| Old Pallas |
Onaght |
Owning |
| Old Pike Bridge |
Oola |
Owroe Bridge |
| Old Port House |
Oolagh Bridge |
Oxgrove Bridge |
| Old Ross |
Oran |
Oysterhaven |
| Old Town |
Órán Mór |
| Old Town |
Oranmore |