Prominent figure in the fourth branch of the Mabinogi. Son of Dôn and brother of Gilfaethwy, Gwydion is a powerful magician like his uncle, Math, who gives his name to the fourth branch. Through his magic he contrives a war between Math of Gwynedd and Pryderi of Dyfed by having his brother Gilfaethwy sleep with the virginal Goewen, Math's foot-holder. Learning of this treachery, Math transforms Gwydion and his brother into, successively, a stag and hind, a boar and sow, and a male and shewolf. Restored again to human form, Gwydion fashions a wife out of flowers, Blodeuwedd, for his protégé Lleu Llaw Gyffes, who may have been his incestuously begotten son. He transforms the trees into warriors in Cad Goddeu [The Battle of the Trees]. Brother of Arianrhod and father of Bleiddwn, Hychdwn Hir, and Hyddwnn.

Bibliography

• Rachel Bromwich, Trioedd Ynys Prydain, rev. edn. (Cardiff, 1978), 400–2

A Dictionary of Celtic Mythology. Copyright © James MacKillop 1998, 2004. All rights reserved.