C
- (Roscommon) Castlestrange Bridge
- (Roscommon) Castleplunket
- (Sligo) Castleore
- (County Galway) Castlemoyle
- (County Leitrim) Castlefore
- (Roscommon) Castlecoote
- (Sligo) Castleconor
- (County Galway) Castleblakeney
- (County Galway) Cashel
- (Sligo) Carrowwilkin
- (Sligo) Carrowreagh
- (Roscommon) Carrowreagh
- (Mayo County) Carrowmore
- (Mayo County) Carrowmore
- (Sligo) Carrowmore
- (Mayo County) Carrowmore
- (County Galway) Carrowmore
- (Mayo County) Carrowkennedy
- (County Galway) Carrigeen
- (Mayo County) Carracastle
- (County Galway) Carrabaun
- (Mayo County) Carnhill
- (County Galway) Carna
- (Mayo County) Carn
- (Mayo County) Carha
- (County Galway) Cappataggle
- (County Galway) Cappalusk
- (Sligo) Cappagh
- (County Galway) Cappagh
- (County Galway) Cappagh