The last King of Leinster, Ireland. aka Dermot Mac Murcha (Browning, Charles. Americans of royal descent, 7th ed. Baltimore : Genealogical Pub. Co., 1969, pg. 67, 339).
aka Diarmaid MacMurchada, Dermod MacMurrough. Succeeded as King of Leinster 1126. Claimed the south of Ireland, 1134. Ravaged the south with great cruelty and abducted Dervorgill, wife of the Lord of Breifne, 1152. Defeated and banished by a combination of chieftains, 1166. His offer to become King Henry II's vassal, if assisted in the restoration of his kingdom, accepted. Returned to Ireland, 1167, having prevailed on Richard de Clare (Strongbow) to assist him, Henry II being unwilling to afford him direct help. Took Waterford and Dublin with the aid of various Norman nobles. Claimed to be king of all Ireland (The concise dictionary of national biography, pt. 1 : from the beginnings till 1900. London : Oxford U. Pres, 1969, pg. 822).
Browning, pg. 443 gives different ancestors for Dermot. www site Directory of royal genealogical data has him as a son of Donnchad, rather than a grandson.