J.W.
Kids with good imaginations are fun! I only lucked into the right combination to keep my kids out of my room so I can't really tell you what I did right. I know when I was a kid the only reason I didn't go to my parents room is they were totally unsupportive. When I cried I was being bullied mom said it was my fault, that kinda stuff. So I wouldn't suggest scaring the child into leaving you alone, ya know, I will ground you if...
The problem is with a good imagination you really see the monsters when you wake up so nothing around you is going to help. I outgrew it by the time I was ten.
Perhaps a clicker she can keep by her bed. Something that won't wake everyone up but gives her the ability to "scare" them away.
Sorry, I feel useless here.