Dictionary of Welsh Biography

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DEINIOL (d. 584 ), saint, founder of Bangor and first bishop in Gwynedd ;

son of Dunawd son of Pabo Post Prydyn , of the same royal line as Urien Rheged Dwyai , daughter of Gwallog ap Lleenog was not his mother but his second cousin. As Deiniol and Maelgwn Gwynedd (q.v.) were contemporaries, so were his grandfather Pabo and the sons of Cunedda Wledig (q.v.) . Pabo , then, must have accompanied them to Wales , not because of any loss of territory but in order to acquire more. According to the place names his clan occupied Anglesey ( Llanbabo ), Caernarvonshire ( Bangor ), and the Vale of Clwyd ( S. Asaph ). This was why Cynfarch and Urien Rheged established themselves there between 550 and 574 . The reign of Maelgwn Gwynedd was the golden age of religion in Gwynedd west of the Conway , being the age of Cadfan , Seiriol , Cybi (qq.v.) , and others; the genealogies of the saints show that it was in the next generation, after the ‘ Yellow Pestilence ’ ( 547 ), that the up-surge of religion took place in Gwynedd east of the Conway . So, Bangor, Caerns. , was Deiniol 's first foundation and Bangor-is-coed, Flints. , was its daughter. If the description given by Gildas to Illtud is correct — ‘praeceptorem paene totius Britanniae magistrum elegantem’ (36) — Deiniol was educated with Maelgwn Gwynedd at Llanilltud ( Llantwit Major ). We do not know by whom he was appointed and consecrated bishop , but according to the ‘ Life of Samson of Dol ’ (q.v.) this was done by the bishops of the Celtic Church and he was allowed to choose his own see — which was, doubtless, Gwynedd . If so, it is probable that the tradition preserved in the ‘ Book of Llandaf ’ attributing this to Dyfrig (q.v.) is probably correct: S. David would have been too young at the time. There is no reason to doubt that Deiniol attended the synod of Brefi . According to the Ann. C. he d. in 584 , but it is possible that this date, like the dates given for the deaths of David and Kentigern , is twelve years later than it should be, in which case the correct date is 572 .


  • Baring-Gould and J. Fisher , The Lives of the British Saints , 326-31, for a summary of the medieval traditions about him;
  • but, for the most part, these are late inventions and it is difficult to reconcile them with the genealogies in Y Cymmrodor , ix, 173-5.


Chancellor John Williams James, D.D., Aber, Bangor

Published date: 1959