The Battle of Camlann is best known as the final battle of King Arthur, where he either died in battle, or was fatally wounded. As the surviving accounts of this battle are all generally little more than legend or myth (and all versions exhibit traces of folklore), some historians doubt this battle even took place.

In most tales, the battle was caused by a knight on one side who drew blade against orders to kill a snake. As the unsheathing of cold steel was against the rules of the truce, both armies subsequently charged at each other, beginning the battle in earnest.

The earliest known reference to this battle is the entry in the Annales Cambriae for the year 537: Gueith camlann in qua Arthur et Medraut corruerunt - "Battle of Camlann in which Arthur and Medraut (Mordred) perished". Later accounts of this battle are in Geoffrey of Monmouth's Historia Regum Britanniae, and in the 13th century Welsh tale, "The Dream of Rhonabwy."

A possible site is Queen Camel in Somerset which is close to the hill fort near South Cadbury (identified by some with King Arthur's Camelot), where the River Cam flows beneath Camel Hill and Annis Hill. However, a number of other identifications have been offered, including Birdoswald near Hadrian's Wall (Latin "Camboglana"), the River Camel along the border of Cornwall, and the River Camlann in Eifionydd in Wales.