Also known as Saint Dervel the Mighty. Confessor (6th century). According to legend he was son of a Welsh chieftain, Hywel Mawr, and brother to Saint Tudwal, Bishop of Treguier, and Saint Arthfael. He followed the profession of arms in his youth, his skill and valor in battle being the theme of contemporary bardic songs. He fought in the battle of Camlan, 537, and later entered the monastery of Llantwit, devoting the remainder of his life to missionary labors. He is held in particular veneration at Llandderfel, in Merionethshire, where his relics were preserved until their destruction by Cromwell. Feast, 5 April.