Anguish (Angwish, perhaps a form of the Irish name Oengus)

   A king of Ireland and the father of Iseult. He seems to have fought against Arthur on the side of the rebel kings at the beginning of Arthur's reign. King Mark of Cornwall owed him allegiance and Anguish collected annual tribute through the enforcement of the Morholt, his brother and renowned warrior. Anguish later may have became a companion of the Round Table and may also be the same warrior as Agwisance.
   He is generally considered a king of Ireland, but it is more likely in my opinion that he was one of the Irish warrior chieftains that captured and set up residence in the western edges of Wales and Cornwall.