C
- (Roscommon) Clera Island
- (Roscommon) Carrickynaghtan
- (Roscommon) Cloonown
- (Roscommon) Cuilleen
- (Roscommon) Cloonfad
- (Roscommon) Cappavuse
- (Roscommon) Coolumber
- (Roscommon) Callowbeg
- (Roscommon) Cornaveagh
- (Roscommon) Creggan
- (County Galway) Callow
- (County Galway) Carrickacummer
- (County Galway) Chapel Island
- (County Galway) Curhownagh
- (County Galway) Carricklahan East
- (County Galway) Carrickarone
- (County Galway) Crockaunroe
- (County Galway) Currywongaun
- (Mayo County) Cloonlaur
- (Mayo County) Capnagower
- (Mayo County) Craigmore
- (Mayo County) Carrickmore
- (Mayo County) Carrickakin
- (Mayo County) Claggan
- (Mayo County) Castlehill
- (Mayo County) Cuilmore
- (Mayo County) Cluain Damh
- (Mayo County) Cuilkillew
- (Mayo County) Crillaun
- (Mayo County) Crumlin