Bagdemagus (pronounced /ˈbægdɛˌmægəs/) is a character in the Arthurian legend, normally depicted as king of the land of Gorre and a Knight of the Round Table. He chiefly figures in literature the father of the knight Maleagant, who abducts King Arthur's wife Queen Guinevere in several versions of a popular episode. Bagdemagus first appears in French sources, but the character may have developed out of the earlier Welsh traditions of Guinevere's abduction, an evolution suggested by the distinctively otherworldly portrayal of his realm. In most versions he is portrayed as a kinsman and ally of Arthur and a wise and virtuous king, despite the actions of his son.
Bagdemagus first appears in French works of the late 12th century, but the principal episode in which he appears, the story of the abduction of Guinevere, developed out of significantly older traditions. Caradoc of Llancarfan's early 12th-century Latin Life of Gildas includes an episode in which Guinevere is kidnapped and taken to the "Isle of Glass", glossed as Glastonbury Tor, by Melwas, King of the "Summer Country". This Melwas is generally understood to be the original of Maleagant, Bagdemagus' son in the French works. Some other texts testify to the early popularity of this story; a version of it is alluded to in the Welsh poem known as "The Dialogue of Melwas and Gwenhyfar", which survives in two variants, and a "Meloas", lord of the Isle of Glass, is mentioned in Chrétien de Troyes' French romance Erec and Enide. Some writers have suggested that Bagdemagus should be identified with Baeddan, mentioned as the father of "Maelwys" in the early 12th-century Welsh romance Culhwch and Olwen. This identification relies on the suggestion proposed by E. K. Chambers that Maelwys is an alternate spelling of Melwas. However, this suggestion is rejected by Rachel Bromwich and Simon Evans, among others, who instead connect Maelwys with the historical Irish prince Máel Umai, son of Báetán mac Muirchertaig.
The character is first mentioned in the 12th century in Chrétien de Troyes' Lancelot, the Knight of the Cart, he is the king of Gore, a mysterious land connected to Logres only by a bridge as sharp as a sword, where many natives of Logres are kept prisoner; again, his son Meleagant abducts Guinevere, who is later rescued by Sir Lancelot. In the romance Sone de Nansai, King Baudemagus is said to be the father of Meleagan, and the son of Tadus.
The story is repeated, without its supernatural overtones, in the later Vulgate Cycle; King Baudemagu is presented as a cousin of Sir Gawain and a friend of Sir Lancelot, who condemns his son's evil deeds and acknowledges that his death at the hands of Lancelot was deserved. In Thomas Malory's Le Morte d'Arthur the link between Bagdemagus and "Sir Meleagraunce" disappears, and Bagdemagus is just another brave knight of the Round Table. He is accidentally killed by Gawain at a tournament. René Bansard (+ 1971) looked on similar legends between king Baudemagu and hagigraphy of Bômer alias Bohamadus in Normandy near Gorron (Gorre of the Arthurian romance), honoured in several parishes. Both are guardians of the marches of realm. One can see the grave of Bohamadus not far from Lonlay Abbey.