This mythological figure appears in early writings of men like Gildas the Monk and the Welsh text "Y Gododdin," but the works of Geoffrey of Monmouth established much of his legend. This man defeated the Saxons to rule over an area encompassing not only the British Isles, but also areas like Iceland and Gaul. He was killed by his nephew Mordred at the Battle of Camlann, and advised by the wizard Merlin. For 10 points, name this monarch, son of Uther Pendragon and husband of Guinevere, who wielded Excalibur and spent his final days at Avalon.
A) King Arthur
B) King Henry VIII
C) King Richard the Lionheart
D) King Alfred the Great