I don't think a good adaptation needs to be a faithful one — if so, The Shining would be shit — and oftentimes can benefit from the opposite. So, there's actually only one of these films where I've read the book and can compare it (see the notes).

Also, only adaptations of books here, so no 12 Angry Men or similar. I'm also not including 2001: A Space Odyssey, since it's only partially based on a short story and the novel was created side-by-side with the film.