This is a very slippery slope as it would be very difficult to prove the movie was not based more on the later comics adaptations with the changes as it is very loosely adapted from the book.
Unfortunately this would also lead to not including series like Buffy, Angel, the Phantom, and others due to the comic being adapted directly from a TV series/book and not the other way around. Are comics being the original source material a hard rule?
The list might be easier to maintain and add to if it was broken down by year, here is a website that includes comic book movies/series/serials by year with distributor.
CLICK ME
I understand completely where you are coming from. Conan is a good example where the movies came out while Marvel was publishing the comic books. But when I read the history of how the Conan movies came about, it appears Oliver Stone rejected the comic-based -script and went with his own. Then later, Milius tore apart Stone's version and kept only certain parts.
While on the other hand, Red Sonja was based on the Marvel Comics character which was influenced by Robert E. Howard's Red Sonya of Rogatino from the "The Shadow of the Vulture" short story.
But I can add John Carter, Tarzan and others that were a combination of novels, comic books and films if everyone wants that. No worries at all.
that'd be a different list of comics based on books/tv/film