Udisha
Stephen King: The Shining (1980)
When The Shining was adapted by Stanley Kubrick, the author actually hated the iconic film! Dubbing it "cold", Stephen King felt the film failed to capture the emotions and characters properly.
Rick Riordan: Percy Jackson & the Olympians: The Lightning Thief (2010)
Rick Riordan did not approve the changes made to the script, prior to the release of the film, directed by Chris Columbus. When it released, the author was further angry and felt the movie had ruined the book.
P.L. Travers: Mary Poppins (1964)
Disney's Mary Poppins went on to become a cult classic but the author of the book got into an argument with Walt Disney himself, for she felt the animation failed to portray Mary Poppins' strength.
Roald Dahl: Willy Wonka & the Chocolate Factory (1971)
Another classic movie where the author felt quite differently. Road Dahl specifically had an issue with Gene Wilder's casting and felt the film did not pay much attention to the hero of the book, Charlie Bucket.