Oaghley - Oakfield - Obelisks - Obriensbridge - Obriens-Bridge - Ocallaghansmills - Oconnell-Bridge - Odoca - Offally - Offaly - Oggal - Oghil - Oghill-Bridge - Oghill-Cross-Roads - Ogonnelloe - Oilean-Ciarrai - Oilgate - Oil-Mill-Bridge - Oldbawn - Oldboleys - Oldbridge - Oldcastle - Oldcastletown - Oldchapel - Oldcourt - Oldgrange - Oldleagh - Oldleighlin - Oldmill-Bridge - Oldstreet - Oldtown - Oldtowndonore - Oldtown-Cross-Roads - Old-Bride-Bridge - Old-Bridge - Old-Chapel-Cross-Roads - Old-Connaught - Old-Courth - Old-Kilcullen - Old-Kildimo - Old-Mountain - Old-Pallas - Old-Pike-Bridge - Old-Port-House - Old-Ross - Old-Town - Old-Twopothouse-Cross-Roads - Omeath - Onaght - Oneills-Cross-Roads - Oola - Oolagh-Bridge - Oran - Oranmore - Oran-Mor - Orchard-Bridge - Oristown - Orkneys-Cross-Roads - Ormond-View - Orristown-Cross-Roads - Oughtagh - Oughter - Oughterard - Oughtiv - Oughtmama - Oulart - Ouley - Oultort - Ourtnagapple - Ouvry-Cross-Roads - Ovens - Ovenstown - Ovoca - Owenbeg - Owenbristy - Owenduff - Owenea-Bridge - Ower - Owgarrif-Bridge - Ownagarry-Bridge - Owning - Owroe-Bridge - Oxgrove-Bridge - Oysterhaven - O-Meith -