I never thought anything lived in the closet or under the bed, whatever, but woke up a few times to scaaaary things. I think I woke up anyway.
Once, I saw three snakes slithering up the blankets from the foot of the bed, and no matter how much I shook the blankets, they wouldn't be flung away.
Once there was a character from Pee-Wee's Playhouse hiding behind the closet door. It was the thing that was a big eyeball on legs, only more monstery. Scared me.
After walking into a cloud of gnats during the day, I woke up one night thinking there were bugs all over me and the wall and was flailing around and screaming. My mom came in and told me there wasn't anything there, and it took a while to convince me.
Oh, and then there was the babysitter that let us watch Aliens (the second one). Had one doozy of a nightmare from those alien samples in the three glass tanks. Carrie the Babysitter came in and calmed me down by telling me she'd never be able to watch us again if I said anything about seeing the movie and having a nightmare. Didn't make me feel better, but stifled me well enough. Thanks Carrie!
Here's the Pee-Wee monster! Its name was Roger and you can see its mouth on the side of... it. And its eye.