Fachtna Fáthach

Fachtna Fáthach ("the wise"), son of Cas (or Ross), son of Rudraige, was, according to medieval Irish legend and historical tradition, a High King of Ireland. He came to power when he defeated the previous High King, Dui Dallta Dedad, in the battle of Árd Brestine. According to some stories he was the lover of Ness, daughter of Eochaid Sálbuide, king of Ulster, and the father of her son, Conchobar mac Nessa, the king of Ulster in the stories of the Ulster Cycle.