What are the sources of the Arthurian myths and legends?

The sources for the Arthurian myths and legends as we know them are found not in 6th Century history but in 11th-14th Century Romances intended to influence the conduct and reputation of real Knights in armour.

These were compiled into Malory's Le Morte d'Arthur in 1485  and have been repeatedly reinterpreted and embellished in literature, the arts and the media.