Wikipedia
Saint Tudwal (died c. 564), also known as Tual, Tudgual, Tugdual, Tugual, Pabu, Papu, or Tugdualus (Latin), was a Breton monk. He is considered to be one of the seven founder saints of Brittany. Tudwal was said to be the son of Hoel Mawr (Hoel I). He travelled to Ireland to learn the scriptures, and then became a hermit on Saint Tudwal's Island, east of North Wales. Tudwal later immigrated to Brittany, settling in Lan Pabu with 72 followers, where he established a large monastery under the patronage of his cousin, King Deroch of Domnonée. Tudwal was made Bishop of Tréguier on the insistence of Childebert I, King of the Franks.
Tudwal is shown in iconography as a bishop holding a dragon, now the symbol of Tregor. His feast day is celebrated on 1 December.