Triffyn Farfog (English: Triffyn the Bearded; born c. AD 385) was a legendary king of Dyfed, son of Aed Brosc [it], a Deisi invader from Ireland, of the dynasty of Eochaid Allmuir.

Triffyn married Gwledyr, the heiress of the British kings of Dyfed, in the mid-5th century and inherited the kingdom.^{[citation needed]}.

He was the reputed father of King Aergol Lawhir. His fraternal nephew, Cormac mac Urb, was the grandfather of Brychan Brycheiniog, eponymous founder of Brycheiniog.