n Arthurian legend, Sir Bedivere (Welsh: Bedwyr; French: Bédoier, also spelt Bedevere) is the Knight of the Round Table who returns Excalibur to the Lady of the Lake. He serves as King Arthur's marshal and is frequently associated with Sir Kay. Sir Lucan is his brother, Sir Griflet is his cousin. The Welsh give him a son and daughter named Amren and Eneuawc. Bedivere, along with Kay and Gawain, is one of the earliest characters associated with King Arthur. His name in Welsh is Bedwyr Bedrydant (Bedivere of the Perfect Sinews).

He is described as one-handed, yet still an excellent warrior. He and Cai (Kay) are two of the six knights chosen to accompany Culhwch on his quest in the Mabinogion romance Culhwch and Olwen and it was said "and although he was one-handed no three warriors drew blood in the same field faster than he".

In the Life of St. Cadoc (c.1100) he was alongside Arthur and Cai in dealing with King Gwynllyw of Gwynllwg's abduction of St. Gwladys from her father's court in Brycheiniog. Because Bedwyr appears in the oldest Arthurian material, some speculate he might have been a real person.

He is one of Arthur's loyal allies in Geoffrey of Monmouth's Historia Regum Britanniae, and maintains this position in much later Arthurian literature. He helps Arthur and Kay fight the Giant of Mont St. Michel, and joins Arthur in his war against Emperor Lucius of Rome.

In several English versions of Arthur's death, including Malory's Le Morte d'Arthur and the Alliterative Morte Arthure, Bedivere and Arthur are among the few survivors of the Battle of Camlann. After the battle, at the request of the mortally wounded king, Bedivere throws Excalibur back to the Lady of the Lake. He then enters a hermitage where he spends the remainder of his life. Bedivere remains a popular character in modern literature. Some modern authors such as Rosemary Sutcliff, Gillian Bradshaw, John M. Ford and Mary Stewart even give him Lancelot's traditional role as Guinevere's lover, Lancelot having been added to the cycle too late to seem historical.

In Bernard Cornwell's The Warlord Chronicles, many of the legendary deeds of Bedivere (such as throwing Excalibur into the Lake; or in Cornwell's story, the sea) are instead carried out by Derfel Cadarn. In the Monty Python 1975 film, Monty Python and the Holy Grail, "Sir Bedevere the Wise" is played by Terry Jones. He is portrayed as a master of the extremely odd logic of ancient times, claiming at one point "...and that [...] is how we know the earth to be banana-shaped."