Saint Tudwal (died c. 564) was a breton monk and was one of the seven founder Saints of Brittany.

Tudwal was said to be a son of Hoel I Mawr. Tudwal travelled to Ireland to learn the scriptures, then became a hermit on what is now called Saint Tudwal's Island East off North Wales. Tudwal later emigrated 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. His feast day is celebrated on 1 December.

Tudwal is also known as

• Tual
• Tudgual
• Tugdual
• Tugual
• Tugdualus
• Tudgualus