This one ghost hunt arc about a man who drank blood to remain alive creeped the shit out of me, that whole anime as a whole just had a creepy aura to it
Hellsing's great, man, but you obviously haven't seen some of these other suggestions. lol
Creepy's a pretty broad description, but Tomoko from WATAMOTE certainly hit home with me. The animated gore in all this other stuff is just unfazing now.