Castlecomer is a former coal mining town in County Kilkenny, Ireland, located in the province of Leinster. The town is positioned at the meeting of N78 and R694 roads about roads north of Kilkenny city in the southeast of the island of Ireland.
At the 2011 census, by the Central Statistics Office, the 30.5 square kilometre Electoral District area of Castlecomer had a population was 2,293, with a population density of 75.2 persons per square kilometre. This saw a decrease of 4.5% from the 2006 figure of 2,407 persons. The Castlecomer rural area has a population of 8,484.
Castlecomer rural area has an area of 23,417 hectares. The town is part of the Castlecomer Plateau. The upland plateau area that surrounds it forms a discrete area. It is bounded on the east by the River Barrow, the west by the River Nore and dissected in the centre by the River Dinnin. The name Castlecomer comes from the Irish ‘Caislean an Chumair’, which means ‘the Castle at the confluence of the Waters’, the "waters" referring to the rivers Deen, Brocagh and Cloghogue while the "castle" refers to the castle built by the Normans in 1171 on the mound opposite the gates to "Castlecomer Demesne".