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Son of Constantine, Arthur's Grandfather, Geoffrey of Monmouth Text and N.N. {Geoffrey of Monmouth Text} Brother of Uther Pendragon, King Arthur's Father, Geoffrey of Monmouth Text; Unnamed Sister of Uther, Geoffrey of Monmouth Text and Aurelius Ambrosius, King of Britain {Geoffrey of Monmouth Text}
A monk, then made King of Britain by Vortigern.