I cut my teeth on horror, weird, and suspense movies as a child as my mother was a fan, so I can't say what monster scares me as I am not "normal" (evil laugh), but I do remember as a small child being afraid of large monsters such as the original Godzilla, Reptillicus, and the like that that could step on your house and crush it. (I am showing my age I guess since I saw them at the movies on their first runs.) I would keep watch over the house roofs for a few days so I could runaway if I saw them. The movie, The Exorcist did not scare me as much as the book did. My mind can make way more scarier things than any movie. I tend to like psycholgical horror more than the physical.