MacCarthy (), also spelled Macarthy, McCarthy or McCarty, is an Irish clan originating from Munster, an area they ruled during the Middle Ages. It was divided into several great branches; the MacCarthy Reagh, MacCarthy of Muskerry, and MacCarthy of Duhallow dynasties were the three most important of these. Their name, meaning "son of Cárthach" (whose name meant "loving"), is a common surname that originated in Ireland. As a surname, its prevalent spelling in the English language is McCarthy. Several variants are found, such as McCarty (most common in North America) as well as Carthy and Carty (though these latter are also the Anglicization of an unrelated name, Ó Cárthaigh). Sixty percent of people with the surname in Ireland originate from County Cork, where the family was very powerful in the Middle Ages. Naming conventions History The origin of the name begins with Carthach, an Eóganacht Chaisil king, who died in 1045 in a house fire deliberately started by one of the Lonergans (who were members of the Eóganacht's arch-enemies, the Dál gCais). Carthach was a contemporary and bitter rival of High King Brian Boru, and what would become known as the McCarthy Clan was pushed out of its traditional homelands in the Golden Vale of Tipperary by the expansion of the O'Brien sept in the middle of the twelfth century. Carthach's son was known as Muireadhach mac Carthaigh (meaning "Muireadhach, son of Carthach"). Such ephemeral patronymics were common at the time. However, when Muireadhach died in 1092 his sons Tadhg and Cormac adopted Mac Carthaigh as an actual surname. Following the treaty of Glanmire in 1118, dividing the kingdom of Munster into Desmond and Thomond, this Tadhg became the first king of Desmond, comprising parts of the modern counties of Cork and Kerry. For almost five centuries they dominated much of Munster, with four major branches: those led by the MacCarthy Mór (Great MacCarthy), nominal head of all the MacCarthys, who ruled over much of south Kerry, the Duhallow MacCarthys, who controlled north-west Cork; MacCarthy Reagh or Riabhach ('grey') based in the Barony of Carbery in south-west Cork; and MacCarthy Muskerry, on the Cork / Kerry border. Each of these families continued resistance to Norman and English encroachment up to the seventeenth century when, like virtually all the Gaelic aristocracy, they lost almost everything. An exception was Macroom Castle, which passed to the White family of Bantry House, descendants of