Wow, it’s been a while since anyone responded to this.
Unlike most kids, I didn’t think of monsters hiding under the bed or in the closet- I thought they were hidden in the walls, waiting until I shut my eyes so they could pop up from the wall, fly towards me, and “dance” around me, judging what kind of a dream I should have each time.
What movie did you watch back then? 
I was a little sneaky and peeked into some of the scary movies my parents watched. (I was a little hesistant to watch Monsters, Inc because at first I thought it was an animated horror movie. Boy, was I wrong.)
But the “jumping out of walls” idea just came to me. I didn’t get it from a movie, at least I think not.
I had two ‘monsters’.
One was that strange black blob like that thing on the moomons (moomins? can’t remember). It was a depressing character on tv, and I felt sorry for it, but also afraid of it at the same time (weird huh?), so sometimes I thought it hung around my house when I was little. In my dreams I had the bizarre urge to both hug and run away from it at the same time.
Later that monster got replaced… by a caveman. Yes, that’s stupid and weird, but it was this miniture caveman all hairy and strange with a nose sticking out of its masses of black hair. When it ‘scared’ me its eyes would pup out all bloodshot and horrible. Definitly human in some ways, but it only came up to my ankle in height. It was just horrible. Didn’t feel sorry for it. I just hated it.
Makes no sense at all, does it? Hah!
Black Widow Spiders. I was terrified of them as a child, and I always imagined them swarming under my bed at night, waiting to strike. Yeah, I had an active imagination.
This was hiding in my closet for about two weeks when I saw this movie at a party in 2005. I wasn’t really scared of monsters when I was little. I was afraid of murderers, crazy ones. Like Leatherface or Jigsaw or Shoko Asahara or Charles Manson.
Oh, heh, I’ve never been afraid of monsters or murderers…
I remember times where I feared disease… yeah I know, strange right? I thought I was going to die from smallpox after seeing a documentary. That gave me nightmares for a day or two. Haven’t always LOVED insects either 
Vampires… another thing I used to be afraid of and the dark. shivers it was creepy what I could imagine lurking there.
I always felt there was a murderer just barely out of sight at the end of the bedpost. For a while, I also checked to make sure there were no aliens in the bathtub.
The monsters under my bed, or at least the ones that took center stage in all my nightmares were the Tyrannosaurus Rex, Velociraptors, the three-headed monster from Hercules, and for some reason, Klingons.
The monsters under my bed were vampires and ghosts. I have no idea why.
Toys. Lots of Toys 
I did. LOL.
Seriously, I used to hide under my own bed. I can still fit under there even now.
As a child though I would hide there from my parents. XD