Toirdelbach Ua Briain

Toirdelbach Ua Briain (1009–14 July 1086), grandson of Brian Bóruma, was king of Munster and effectively high king of Ireland. His father Tadc was killed in 1023, probably on the orders of his half-brother Donnchad, who seized Munster.

Allied from the 1050s with Diarmait of Leinster, he wore Donnchad down and in 1063 drove him into exile to Rome. After Diarmait's death he became Ireland's master, installing his sons Muirchertach in Dublin and Diarmait in Waterford and making and unmaking kings of Connacht. He died at Kincora in 1086, leaving Muirchertach his successor.