Kilkenny Castle is a castle in Kilkenny, Ireland. It was the seat of the Butler family. Formerly the family name was FitzWalter. The castle was sold to the Irish government in the middle of the 20th century for £50. It has since been refurbished and is open to visitors. Part of the National Art Gallery is on display in the castle. There are ornamental gardens on the town side of the castle, and extensive land and gardens to the front.

Kilkenny castle was the venue for the meeting of the General Assembly, or parliament, of the Confederate Ireland government in the 1640s.

Awards and conferring ceremonies of the graduates of "Kilkenny Campus" of National University of Ireland, Maynooth have been held at the castle since 2002.