Wethenoc was a 5th-century saint of Welsh origin who is also recognized within the Breton tradition. Born in Wales to Prince Fragan of Dumnonia and Saint Gwen, he was raised in Ploufragan, located near Saint-Brieuc in northwestern France. He grew up alongside his siblings, including his brothers Winwaloe and Jacut, as well as his sister Creirwy. During his youth, he received his education from Budoc of Dol on the Île Lavret.