I had an imaginary friend when I was a kid. Her name was Katy and she was a ghost who lived under the stairs. When I walked down them she gave me visions of people falling from the balcony to their death. She was really mean and told me nobody would ever love me. She would make me sleep with corpses because she thought it was funny. Only when I would visit her underneath the staircase would she let up the images of death and play nice. She went away when we moved though.
I got really good at imagining puppies and unicorns to keep the visions away.
Edit: rereading this it sounds like a joke, but it's true. I don't believe in ghosts so...I was a tortured little kid, lol. Gawth4lyfe.