A "Magician" as in the Blackstone sense or a "Magician" such as Merlin & Gandolph?
The latter will be far easier to find material on unless you want to look at characters within a story such as the Artful Dodger in the Olive Twist tale. . . now he's got a story! A child pick-pocket and street hustler. . .
When it comes to the latter, you might look at "The Crystal Cave" or technically "Mists of Avalon" (though that focuses more on the Arthurian saga than Merlin himself)
I'm not certain, but you may check to see if films line "Nightmare Alley" have been turned into Novels or vice-versa, the film is based on an existing story. I do know that magicians have been the "bad guy" in a handful of films but I'm not positive on source.
Hope this helps, though