[W gwyn, white, fair, holy].
Mythological king of Welsh tradition whose stature diminishes over the centuries with the advance of Christianity. In the oldest literature he is a ruler of Annwfn or the Otherworld and has within him the ferocity of demons or fiends. Despite the meaning of his name, Gwyn bears a blackened face while leading the pack of fairy dogs known as cw^n annwfn. Culhwch must enlist his support in the hunt for the great boar Twrch Trwyth in Culhwch ac Olwen. In the same poem Arthur condemns Gwyn to a continual combat with Gwythyr fab Greidawl for the love of Creiddylad each Calan Mai [May Day] until the end of time. Gwyn has abducted Creiddylad, the daughter or Lludd Llaw Ereint, a double for Gwyn's father, Nudd, a point unheeded in the story. After the 16th century Gwyn becomes the king of the tylwyth teg [fair folk], i.e. fairies. As commonly noted, the name Gwyn ap Nudd is philologically related to that of Fionn mac Cumhaill, who is descended from Nuadu (Airgetlám or Necht). T. F. O'Rahilly speculated (1946) that both Gwyn and Fionn are identical with the divine hero Lug Lámfhota. Gwyn ap Nudd is the title of one of the most notable poems of the Welsh writer H. Elfed Lewis (1860–1953).
See Idris L. Foster, ‘Gwynn ap Nudd’, in Duanaire Finn, iii, ed. Gerard Murphy, Irish Texts Society, no. 43 (Dublin, 1953), 198–205;Jenny Rowland, Early Welsh Saga Poetry (Cambridge, 1990).