Was said by Annales Cambriae to have been a great-grandson of Cunedda, and to have died of plague c.547. He was known as Maelgwyn Hir (‘the Tall’). Gildas, writing as a contemporary, launched a bitter and sustained attack upon him as Maglocunus: ‘first in evil … mightier than many both in power and malice’. He accused Maelgwyn of seizing the throne by murdering his uncle, cohabiting with his nephew's wife, and retiring to a monastery but recanting to return to his ‘disgusting vomit’. ‘I call it scandalous’, Gildas concluded, rather feebly.