Congal Cennmagair (d. 710), son of Fergus Fánat and king of Tara, belonged to the dynasty of Cenél Conaill. Although his father did not, it seems, achieve political prominence, his grandfather Domnall (qv) (d. 642) son of Áed (qv) had reigned as king of Tara. Congal, whose sobriquet presumably related to his birthplace in Co. Donegal, had come to prominence at least by the mid 690s. He apparently led Cenél Conaill while his cousin Loingsech (qv) son of Óengus was king of Tara; on that account he was a witness to the Law of Adomnán (qv), which was promulgated c.697.
He succeeded to the kingship of Tara when Loingsech was slain in 704. Middle Irish regnal lists assign him a reign of eight or nine years, which may take account of an earlier role as sub-king to his cousin. While there is no record of Congal's wife, he had at least three sons, Donngal, Flann and Conaing. He is also credited with an unnamed daughter who, according to a story in the Fragmentary Annals (§177), was a nun, but became the lover of Cenél nÉogain ruler Fergal (qv) son of Máel-dúin, and was the mother of his son Áed Allán (qv). This alleged relationship may be significant in the light of the dynastic change that followed Congal's death, although it is at variance with the ‘Banshenchas’ (lore of women) tradition.
There are some indications that, shortly after his accession, Congal resumed traditional Cenél Conaill aggression against the Connachta. Otherwise, the highlight of a relatively undistinguished reign came in 707, when he renewed hostilities against the Laigin. It is claimed in ‘Betha Adamnáin’ (§10) that this initiative was taken in collusion with Cellach Cualann (qv), overking of Leinster; along with the latter, Congal is said to have earned the curse of Adomnán. The fact remains that Congal did lead a hosting whereby the border territories of Leinster were devastated, although no lasting result would seem to have been achieved. Congal died suddenly in 710, apparently of a fit. His three sons died in quick succession between 731 and 733, so that his immediate line lost significance in dynastic politics. Meanwhile, the kingship of Tara passed to the above-mentioned Fergal son of Máel-dúin, of Cenél nÉogain.