[Sculpt]

I find categorizing films as fun.

This is the scenario... you work at a film rental place that separates their films by genre. So if I had to pick a shelf for these, I'd go:

Horror:
Battle Royale - the killing scenes are the longest part of the film
American Psycho - the title and subject are very horror in US

Sci-fi:
Predator - space alien, Arnold, big budget, lot's of gadets and effects
Terminator - time travel and what a cyborg would do, decisions and honor, very sci-fiction.

Thriller:
Se7en - rides on the film thrills, mostly about the detectives. I also consider Horror.
Silence of the Lambs - rides on the thrills and intrigue and puzzle of the killer, Hannibal and Clarice.
Cape Fear - Don't remember it well enough... but title/story is more historically Thriller.

Drama:
Donnie Darko - it's more mysterious than thriller or horror. The time travel is so obscure. It's more of a drama to me.