Zombies (The few I've seen have been missing body parts, covered in blood, and just being all around gross and scary)
The Flood from Halo (They just creep me out)
My little sister (I'm kidding, she's not a monster XD)
I can't think of any more at the moment, but I'll probably post again later to add to the list. Or edit this post. I don't like thinking about stuff that scares me, so it's probably going to either be after I am no longer able to edit this post, or never.
