Constantine was a 6th-century ruler of Dumnonia in sub-Roman Britain, later remembered in legend as a king of all Britain. While historical accounts from the monk Gildas describe him as a tyrannical figure who committed various sins, including the murder of two youths in a church, later traditions transformed his legacy. He is often identified as a king who renounced his throne to become a monk, a figure who is venerated as a saint in various regions including Cornwall, Wales, and Ireland.