Reading the Livejournal of the late science fiction author/poet/critic/children's story writer Thomas M. Disch, came across the nugget that he wrote a script for Disney, King of the Kalahari, which became The Lion King.
He says between the collusion/skullduggery of Disney and various agents he was screwed out of credit and royalties. The manuscript was offered for sale as a one-off original literary property at the time of the Livejournal. The seller, James Cummins, no longer offers it -- would be curious to know who has it and how much was paid.
Disch's book The Brave Little Toaster became a "cult," early CGI film that launched the careers of various Pixar hacks. (Haven't seen it.) He got credit for that one, at least.