Sanctan was the son of Sawyl Penuchel, a king in Northern Britain. He is said to have been a disciple of Saint Patrick, though this is chronologically impossible. He was an active missionary in Cumbria, before becoming Bishop of the unidentified Cell da les (or 'church of the two forts'). This may be Kill-na-Sanctan near Dublin or on the Isle of Man, where the civil parish of Santon is named after him. His feast day is on 20 May.