Elffin ap Gwyddno

In Welsh mythology, Elffin ap Gwyddno (Welsh, also Elphin) was a son of Gwyddno Garanhir, 'Lord of Ceredigion'. The earliest example of the name occurs in several of the mythological poems attributed to Taliesin in the Book of Taliesin. The date of their composition is uncertain but probably predates the Norman conquest. Several late medieval compositions refer to Elffin and Taliesin in more detail.

The variant spelling 'Elphin' may refer to Saint Elphin, the town of Elphin, County Roscommon, Ireland or the Diocese of Elphin, cathedral in Sligo Town, Co. Sligo, Ireland. Elphin is also a village in Sutherland, Scotland.