Died c. 564. One of the Seven Patron Saints of Brittany. The Welsh monk Tugdual was one of the sons of King Hoel I Mawr (the Great). He travelled to Ireland from his father's home in Britain to learn the scriptures before becoming a hermit on Ynys Tudwal (St.Tudwal's Isle East) off the Lleyn Peninsula in North Wales. He later immigrated to Leon in Brittany and settled at Lan Pabu with some seventy-two followers. Here he established a large monastery under the patronage of his cousin, King Deroch of Domnonee.
From here, Tugdual travelled throughout Brittany evangelising the local population. He founded the Monastery of Val Trechor at Treguier and had the foresight to go to Paris and have his land grants ratified by King Childebert of the Franks. The monarch insisted that Tugdual be made Bishop of Treguier where he is still venerated, especially around Leon. It was at Treguier that he died in 564. His shrine can still be seen in the Cathedral.