Claim: Donyarth was a king of Cornwall who drowned in 875 as a punishment for collaboration with the Normans.
Evidence: Donyarth (Latin: Doniert) or Dungarth (died 875) was the last recorded king of Cornwall. According to the Annales Cambriae, he drowned in 875. His death may have been an accident, but it was recorded in Ireland as a punishment for collaboration with the Vikings, who were harrying the West Saxons and briefly occupied Exeter in 876 before being driven out by Alfred the Great following the victory of Odda, Ealdorman of Devon at the Battle of Cynwit in 878.