No Country for Old Men is probably one of the most horrific movies I've seen. And it's not because it's overtly scary or the villian is on the top end of creepy villains (though both of these are true). It's the subtext, the simple nature of the actions of the movie. The fact that Chigurh (the villain) is completely evil yet he seems to follow more rules than the supposed hero.
It's super disturbing and the movie is a masterpiece.