The Sword in The Stone by T.H. White, the first book of The Once and Future King[?], is a novel about a young boy named Arthur who befriends a magician named Merlin. The Walt Disney Company made an animated movie about it in 1961. This movie introduced Mad Madam Mim who later appeared in a lot of Disney comics. The movie is entertaining, but ignores White's carefully-constructed moral lessons in favour of visual gags.
A BBC radio adaptation in 1982 starred Michael Hordern as Merlin. Hordern had already starred as another great literary wizard, Tolkien's Gandalf, in the BBC's Lord of the Rings (1981).