Toirdelbach mac Murchada meic Briain  Toirdelbach mac Murchada meic Briain (c. 999 – 23 April 1014) was the grandson of Brian Boru and one of the leaders of the Dál gCais army at the Battle of Clontarf. Toirdelbach was the son of Murchad mac Briain, the putative heir of Brian.