I was deathly afraid vampires were going to sneak into my house at night and give me the S U C C. So I used to sleep with a pillow around my neck, as if ol' Count Drac couldn't just yank the pillow away. I also fully believed vampires couldn't come inside unless invited in but that logic didn't get in the way of me still believing they were going to break in somehow.
When I was like 4 I had an incredibly vivid and terrifying dream that on paper sounds absolutely ridiculous but scared the shit out of me as a kid. I dreamt that a band of orangutans had gotten into our house and were hiding all over the place: in the walls, under the kitchen table, behind the fridge, behind picture frames etc. and every now and then they'd jump out of their hiding spot and attack us. It didn't result in like a long-lasting fear or anything, in fact orangutans are my favorite animal, but to this day when I think back on that dream I feel a little hint of fear.