What, no Doctor Who?
"Blink" messed a lot of people up (but it's way overhyped, so maybe you shouldn't bother by now). "Silence in the Library" was excellent. "The Impossible Planet" really screwed with me, at least the first half of it. A lot of Doctor Who is campy, but that just means that the honestly scary ones that come out of nowhere really nail you.
Personally, I've found "Midnight" to be the scariest one.
I haven't seen every single Dr. Who episode, the scariest (and my personal favorite) episode was the one in WWII London with the kid in the gas mask saying "Mommy?"
Jesus Christ, that episode creeps me the fuck out.
It was in a recent season with Rose, and he was bald, and a cheeky bastard.
However, I am under the impression that he was a cheeky bastard in all of them.
Also, just watched The Thing (the 1980's version), and I can't say it was that great. It would have been better if everyone freaked out more than just "Oh wow, that dog just turned into some kind of mutated flesh horror thing. Oh well, flamethrower!"
Like people actually went insane from that. I probably would. Well... I would go
more insane. And no, Blair being strange and hitting things with axes does not count as insane, because he still
dismantled the helicopter, and some other stuff.