Bécc Bairrche (d. 718), son of Blathmac and overking of Ulaid, belonged to the Dál Fiatach dynasty. One of the seven sons of Blathmac (qv) son of Máel-Cobo, who had died (670) as overking of Ulaid, Bécc owed his sobriquet to the district of Bairrche, perhaps the area where he was fostered. Bécc was married to Conchend, daughter of his father's first cousin Congal Cennfhota (qv), by whom he had seven sons. He apparently had at least three other wives, by whom he had a further five sons. One of his later wives was Barrdub, daughter of Lethlobar son of Eochaid Iarlaithe king of Dál nAraide.
Bécc first came to prominence (674) when he slew his father-in-law Congal Cennfhota, who had succeeded to the kingship of Ulster on Blathmac's death. At this stage, it would seem that Bécc Bairrche had insufficient power to assume the provincial overkingship, which was taken by Fergus son of Áedán of the rival dynasty of Uí Echach Cobo. Bécc clearly emerged, however, as the dominant dynast of Dál Fiatach during Fergus's reign. He may well have encountered opposition from the faction of the late Congal Cennfhota, whose daughter Conchend had formerly been married to the king of Tara, Fínshnechtae Fledach (qv). In 679 Bécc opted to strike against Fínshnechtae; he was repulsed at Tailtiu (Teltown, Co. Meath), but would appear not to have suffered lasting damage. In 692 Bécc Bairrche succeeded unopposed to the overkingship of the Ulstermen. In 703, at the battle of Mag Cuilind on the Ards peninsula, he defeated a British force from the Isle of Man, probably composed of adventurers displaced from the kingdom of Rheged in southern Scotland by the Northumbrian conquest. On this occasion a British leader, the son of Radgann, was slain.
Bécc Bairrche abdicated in 707; according to the Annals of Ulster he ‘assumed the pilgrim's staff’. He was followed in the provincial kingship by Cú Chuaráin, king of Dál nAraide, who did not last very long, being slain (708) by the Dál nAraide themselves. Bécc Bairrche's son, Áed Rón (qv), then became king of Ulster, reigning 708–35. Of Bécc's other sons, Dubthach was slain (712), and two were responsible for defeating the Uí Echach Cobo (714).