The name comes from the Irish MacCarthaigh, derived from carthach, which means loving. The original Carthach was King of Cashel in Co. Tipperary about 1040.

In Co. Cork, the famous Blarney Castle, where visitors can be blessed with the gift of the gab, was originally a MacCarthy stronghold. The castle was built in 1446 by Cormac MacCarthy and was owned by the family until the early 17th century.

In north Co. Cork, just outside the town of Kanturk, are the impressive ruins of Kanturk Castle, begun  c. 1601 by a local chieftain, MacDonagh MacCarthy. It was to have been the biggest house ever built for an Irish chieftain, but the British government ordered a halt to the construction work. MacCarthy was so annoyed that he smashed all the blue glass tiles that had been made for the roof, and the castle was left unfinished, without roof or floors.

The present head of the family is Terence MacCarthy, born in Belfast in 1957, a painter living mainly in Tangier in Morocco.