The Gossip Girl star doesn't just believe in ghosts – she's seen one! "It's a crazy story. I took a picture of one," Momsen says. "My mom grew up in Devil's Lake, N.D., and her next door neighbor died. She was wealthy and her belongings got put in a museum. So I went ghost hunting and took pictures and talked to her and all this stuff. And there are actually two images that I took, one of a hand on a typewriter and one of her entire body in a window."