But did Arthur ever really draw breath? Or is he just a composite of all those virtues and strengths which have, over the centuries, been deemed the very essence of enlightened leadership?
The first literary reference to Arthur appears in a poem written in the late sixth century by a bard called Aneirin. His poem, Y Gododdin, refers to a Celtic war chief who was fighting Anglo Saxon invasions in the late fifth or early sixth century.
Further histories made fleeting references to an Arthur but the most significant was by Nennius, whose History of Britain attests to Arthur's military prowess, securing no less than 12 major victories in battle. A history of Wales written in around 955 not only claims Arthur existed but also specifies when and where he died (537 at the Battle of Camlann).
There seems to be general agreement that if Arthur was flesh and blood, he would have been a Celt. But there is little agreement on which part of Celtic Britain he hailed from.
Most familiarly, and contentiously, Arthur is believed to have lived at Tintagel in Cornwall and a considerable portion of the Duchy's tourist trade depends on propagating this view. The basis for this location is down to Geoffrey of Monmouth (1100-1155), whose History of British Kings gave all the mythmakers that followed (from Malory and Tennyson, to T H White and Walt Disney) the basis for a rugged and romantic hero who lived in a rugged and romantic castle. Geoffrey aside, Arthur also finds himself claimed variously by Northumberland, Wales, and most recently Scotland. Native tales and early poetry from Wales refer to an Arthur whose adventures share more than a passing resemblence with that other early roisterer, the Irish hero Finn mac Cumaill.
So no Arthur, no Merlin and no Camelot then? Last year, English Heritage made the claim that the story could be true after all, as archaeologists had found something to link Arthur to Tintagel. The "proof" was an unprepossessing piece of broken slate on which is inscribed in barely-legible Latin "Artognou, father of a descendant of Coll, has made this".
Geoffrey Wainwright, English Heritage's chief archaeologist says that the word Artognou is close enough to Arthur to conclude that they were one and the same.
And one of the diggers, Christopher Morris, professor of archaeology at Glasgow University, says that the slate is the 6th-century equivalent of a blue plaque: Arthur of Camelot, knight, lived here.
You can understand their excitement, but it still falls a long way short of what science would require as evidence. Mike Baillie, professor at the Palaeoecology Centre School of Archaeology at Queen's University, Belfast, believes that at least one aspect of Arthurian legend may have a basis in fact.
It is to be found in the body of ancient trees, whose rings show that the date of Arthur's death coincided with a dark age, when crops failed and people starved. Baillie thinks this was due to a comet, but the wastelands that resulted would have corresponded with those in the legend of the search for the holy grail.
One of Arthur's enduring charms is that he's coming back. As Malory says: "Yet somme say in many partyes of Englond that King Arthur is not deed. But had by the wylle of our Lord Jhesu in to another place, and men say that he shal come ageyn and he shal wynne the holy crosse."