Gofannon (Welsh pronunciation: [ɡɔˈvanɔn]) is a Middle Welsh reflex of Gobannus, one of the deities worshipped by the ancient Celts. He features in Middle Welsh literature as a great metal worker and as the son of Dôn. His name can be compared with the Old Irish gobae (gen. gobann) ‘smith’, Middle Welsh / Cornish / Breton gof (pl. gofein) ‘smith’, Gaulish gobedbi ‘with the smiths’, all of which are cognate with Lithuanian gabija ‘sacred home fire’, gabus ‘gifted, clever’. His apparent counterpart in Irish mythology, Goibniu, in addition to his duties as a smith, also takes on the role of a divine hero who brewed an ale of immortality, in addition to being an architect and builder.

In Welsh mythology, Gofannon killed his nephew, Dylan Ail Don, not knowing who he was. One of the tasks given to Culhwch if he were to win the hand of Olwen was to get Gofannon to sharpen his brother Amaethon's plough.

Rankine and d'Este (2007), examining Talieisin's First Address from the Red Book of Hergest, also allude to Gofannon being a magician, with the First Address stating:

Middle Welsh
neubum gan wyr keluydon
gan uath hen gan gouannon
gan euuyd gan elestron
ry ganhymdeith achwysson
blỽydyn ygkaer gofannō.

Modern English
I have been with artful men
With Math or with Gofannon
With Eunydd, with Elestron
In company with Achwyson
For a year in Caer Gofannon.