The surname O’Brien is ‘O’Briain’ in Irish, meaning descendant of Brian (Boru). The name means ‘exalted one’ or ‘eminence’. It is among the ten most frequently found in Ireland and derives from the 10th century King of Ireland, Brian Boru. In 976 Brian Boru secured control of the Dal gCais tribal grouping based in the Clare/Limerick area, and two years later defeated and killed the Eoghanacht king of Munster.
He then waged deadly war on the kingdoms of Connacht, Meath, Leinster and Breifne and eventually secured submission from all but the northern Ui Neill, the Leinstermen and the Vikings. His remarkable career as High King of Ireland ended with his death on the field of the battle of Clontarf (1014) when the Norsemen were finally subdued. His victory at Clontarf united all of Ireland, nominally at least, under a single leader, though Brian himself was slain. It is not surprising that Brian’s harp went on to become the model for the national emblem of Ireland.