John Dongan [Donegan, Donnegan, Donkan, Duncan] (died 1413) was a medieval Manx prelate. After holding the position of Archdeacon of Down, he held three successive bishoprics, Mann and the Isles (Sodor), then the see of Derry and lastly, Down. He resigned his last bishopric in 1413, and died afterwards at an unrecorded date. He was the last bishop of the united diocese of Sodor, which split into the "Scottish" and "Irish" (Manx) parts because of the Western Schism.