I mainly read autobiographies & biographies.
If it’s not a biography then its probably a book that was made into a film.
I've got the books to my three favorite films
I’ve got 'American Psycho', 'Fight Club' and 'Stand by Me' (The Body)
The books tend to delve a lot deeper, (or just get sicker in the case of American Psycho)
But I read all of these after I'd seen the films.
The only one I read before I'd seen the film was 'Davinci Code'