Wethenoc or Gwethenoc or Guethenoc was a 5th-century pre-congregational Breton saint.
[1][2][3] [4] A son of Prince Fragan of Dumnonia and Saint Gwen the Three-Breasted of Brittany, he grew up at Ploufragan near Saint-Brieuc (in northwestern France) with his brothers, Winwaloe and Jacut.
They were later joined by a sister, Creirwy.
He was educated by Budoc of Dol on the Île Lavret near Paimpol.
[5] Wethenoc was also the half brother of Cadfan.