A Welsh saint, son of King Ceithfalt of Morganwg or Southern Wales, flourished probably in the sixth century. He was a liberal benefactor of the church of Llandaff. He resigned the government to his son Meurig and devoted himself to religion and contemplation at Tintern in Monmouthshire. When, however, the Saxons under Ceolwulf crossed the Severn and pressed hard upon Meurig, Tewdrig left his solitude and gained a brilliant victory at the head of his old troops, but was killed in the main battle. A church was erected over the grave of the royal martyr; it was called Marthyr Tewdrig and is now Mathern at the junction of the Rivers Wye and Severn. The day of his death is 3 January; the year is uncertain, the dates 610, 577, 527, or even 470 being given.
GODWIN, De praesulibus Angliae (London, 1616), 619; REES, An Essay on the Welsh Saints (London, 1836), 183 sq.