Dyfodwg

Dyfodwg, or Tyfodwg, was a 6th-century Welsh saint. He is one of the three saints from whom the ancient parish of Llantrisant takes its name, and possibly the patron of the parish church of Llandyfodwg in Glynogwr, between Blackmill and Gilfach Goch in Bridgend, and gave his name to the ancient parish of Ystradyfodwg.
Some records state Dyfodwg was a Breton monk, while others that he was born within the Glamorgan area. Iolo Morgannwg states that Dyfodwg founded a church at Ystradyfodwg and was a disciple of Illtyd at Llantwit Major. However, there is no record of any church being dedicated to him in Ystradyfodwg itself, leading some to suggest that the parish was named, not for a saint, but a local chieftain. One legend records that Tyfodwg was a chieftain promised sainthood by the monks at Penrhys.
According to Rice Rees Tyfodwg was one of the associates of Cadfan, though the family line in the Cambrian Biography, is inconsistent with known chronology. His patronal feast is kept on 25 June.