Trahaearn ap Caradog (1044–1081) was a King of Gwynedd. Trahaearn was a son of Caradog ap Gwyn, ruler of Arwystli (in the south of present-day Montgomeryshire, Wales), a small state, on the south-western border between Gwynedd and Powys. He was born in 1044 in Arwystli, and died in 1081 in Mynydd Carn in Pembrokeshire, at the Battle of Mynydd Carn.