Undin (from Undines, female water spirits), from a filipino horror movie I watched when I was really young (around 6 or 7). It scared me so bad, I refused to go to the toilet without my dad on the other side of the door for months. (A scene on the movie was one of an undin dragging a victim down through a toilet)
Although THAT doesn't scare me anymore. I just thought I'd mention it, because it literally scared me shitless once.
Something that does scare me until now was from somewhere I don't even remember. Either it was a movie, a tv show, or a book. It was probably a japanese horror ghost movie, but I can't really remember. It's a Japanese creature. The Noppera-bo
, faceless monsters who impersonate people you know.
If something like a Noppera-bo haunting happens to me in real life, I'd go insane right on the spot.