Just watched this again, and I'm shocked it's never been done, let alone suggested. It's a French historical drama/supernatural/mystery/action film that is technically based on the Beast of Gévaudan, but is so completely bonkers that it defies words.
True story: There was a large animal that killed a lot of people in Gévaudan, France in the 1700's. Most people theorized it was a large wolf or wolf hybrid, though a couple have made a case for it actually being a lion.
The movie: A naturalist from the king's court comes to help figure out what the beast is, along with his native American sidekick who knows martial arts and has slightly magical powers. Over the span of two hours, there's melodrama, intrigue, random martial arts battles, totally insane camera movements, unexplained mysticism, conspiracies, and bizarre CGI. It's made all the more surreal because it's in French, so it feels like it's supposed to be sophisticated, but it's more jarring than anything.