King Arthur actually appears
in an animated Christmas special together with Santa Claus in The
Secret World of Santa Claus: Santa Claus' Memoirs, one of 4 episodes
on the 2002 DVD.
"Santa Claus has agreed
to be interviewed by a journalist. She asks him about the greatest
Christmas present ever. Santa tells the story of how he and Merlin the
Magician gave the young King Arthur his sword Excalibur. The Earl of
Gruzzle - Gruzzlebeard's ancestor - was not too happy about it!" Most
of the plot concerns a dispute between Merlin and the Lady of the Lake.