Muircheartach Ua Briain, son of Toirdelbach Ua Briain and great-grandson of Brian Boru, was King of Munster and later self-declared High King of Ireland.

Brian Boru was an Irish king who ended the domination of the High Kingship of Ireland by the Uí Néill, and possibly ended Viking invasions of Ireland. Brian Boru was mentioned in Annals of Inisfallen and Chronicon Scotorum as "Brian mac Cennétig". The name Brian of Bóruma or Brian Boru was given to him posthumously Brian built on the achievements of his father, Cennétig mac Lorcain, and especially his elder brother, Mathgamain. Brian first made himself king of Munster, then subjugated Leinster, eventually becoming High King of Ireland. He was the founder of the O'Brien dynasty, and is widely regarded as one of the most successful and unifying monarchs in medieval Ireland.