Cadfan ap Iago (c. 580–625; reigned from c. 615) (Latin: Catamanus; English: Gideon) was a King of Gwynedd. The son of King Iago, he likely assumed the crown of Gwynedd around 615, shortly after the Battle of Caer-Legion (also known as Chester), during which the forces of Gwynedd were defeated by Ęthelfrith of Bernicia. Despite Ęthelfrith's military victories, Cadfan continued to provide haven for Edwin of Northumbria, whom Ęthelfrith regarded as a major threat.
Cadfan was generally considered to have been a wise and just ruler, noted for his ability to maintain the rule of law and peace during an increasingly hostile period in British history. His memorial stone at Llangadwaladr Church in Anglesey refers to him as "the wisest and most splendid of all kings." He was succeeded by his son Cadwallon.
He was one of the last of the legendary kings of the Britons as accounted by Geoffrey of Monmouth.
|- style="text-align: center;"
| width="30%" |Preceded by:
Saxon Interregnum
| width="40%" style="text-align: center;" |Mythical British Kings
| width="30%" |Succeeded by:
Cadwallon
