Deiniol [St Deiniol, Daniel] (d. 584), bishop of Bangor and founder of monasteries, is first recorded in the early ninth-century Irish martyrology of Tallaght, where his feast day is given as 11 September; this agrees with almost all the later Welsh calendars. In the martyrology of Tallaght he is given as Deiniol, bishop of Bangor, but in his obit in the Annales Cambriae, s.a. 584, he is Daniel of the Bangors. This suggests that he was already known as the patron saint of his foundation, Bangor Is-coed, the monastery mentioned in a famous story in Bede's Historia ecclesiastica, about the battle of Chester, assigned by the Annales Cambriae to 613, nearly thirty years after Deiniol's death. According to the story as it reached Bede, the number of monks was so great that the community had been divided into seven sections, with no section having fewer than 300 members. Entries in Irish annals referring to Bangor in Britain and the fact that he was one of only three Welsh saints to be included in the martyrology of Tallaght also indicate the importance of his foundations in the pre-viking period.
There is, however, no narrative account of Deiniol surviving other than the brief résumé in the lections for his feast, copied by a prominent north Welsh antiquarian, Sir Thomas Wiliems, between 1594 and 1610. The version given in these lections corresponds closely to the story in a poem in praise of Deiniol by Sir Dafydd Trefor in 1527. The important aspect of the lections is that they show Deiniol as a hermit close to Pembroke before he became a bishop. George Owen's Description of Pembrokeshire mentions St Daniells chappell neere Penbrok (Owen, 1.108). In 1620 a Cae Ffynnon Daniel (Field of Daniel's field) was recorded at Bangor Is-coed. It appears, therefore, that, although Deiniol came to be predominantly associated with the cathedral church of Bangor, his cult remained active in south-west and north-east Wales right up to the Reformation. The wide range of the cult is also echoed by the importance and range of his supposed saintly kinsmen: his father, Dunod (Donatus), is said to have been a son of , ancestor of a number of saints, including and (the principal saint of Powys). Through his mother, Dwywai, he may have been linked with further saints, predominantly in the north. His name is commemorated in the national monument to W. E. Gladstone at Hawarden, Flintshire: St Deiniol's Library.
T. M. Charles-Edwards
E. Phillimore, ed., The Annales Cambriae and Old Welsh genealogies, Y Cymmrodor, 9 (1888), 14183 [version A], esp. 15269 · R. I. Best and H. J. Lawlor, eds., The martyrology of Tallaght, HBS, 68 (1931) · P. C. Bartrum, ed., Early Welsh genealogical tracts (1966) · D. Trefor, cywydd to Deiniol, 1527 · S. Harris, ed., Liturgical commemorations of the Welsh saints [pt 1], Journal of the Historical Society of the Church in Wales, 5 (1955), 522 [copied by T. Wiliems, 15941619, into Peniarth MS 225, fols. 15560] · J. E. Caerwyn Williams, Buchedd Ddeiniol Sant, Transactions of the Caernarvonshire Historical Society, 10 (1949), 12335 [Welsh edn and trans. of Legenda novem lectionum…] · G. Owen, The description of Penbrokshire, ed. H. Owen, 4 vols., Honourable Society of Cymmrodorion, Cymmrodorion Record Series, 1 (18921936), pts 13 · S. Baring-Gould and J. Fisher, The lives of the British saints, Honourable Society of Cymmrodorion, Cymmrodorion Record Series, 2 (1908), 32531 · E. R. Henken, Traditions of the Welsh saints (1987) · E. R. Henken, The Welsh saints: a study in patterned lives (1991)