Brian Boru, Or Boroihme("Brian of the tributes "), the most celebrated of native Irish kings, born about 927, slain at Clontarf on Good Friday, 1014. He was the son of Kennedy, king of Munster, and succeeded him in 978. His first exploits were against the Danes of Limerick and Waterford. He confined them within the limits of those cities, and made them pay tribute in pipes of wine. In 1002 he made himself ard-righ, or supreme monarch of Ireland, putting aside the legitimate families, the O'Neills and O'Melaghlins, and imposing upon the subordinate kings heavy tributes in cattle, hogs, iron, mantles, and wine. His palace was at Kincora, in county Clare, near the present town of Killaloe. He had also palaces at Tara and Cashel. He caused a road to be constructed round the coast of the whole kingdom. In the latter part of his reign Maelmora, the king of Lein-ster, revolted and called in the Danes to his assistance. Brian Boru repulsed the allied Danes and Leinstermen at Clontarf, and died on the battlefield. His son Morrogh also fell in the same fight. The Danes never regained any independent position in Ireland after this defeat.

An ordinance of his prescribed that every one should adopt as a surname the name of his father, and thenceforth surnames became permanent in Irish families.