The Phantom of the Maine State Library.
Since I was super-popular in high school*, I spent a lot of time hanging out at the Maine State Library.
I did a lot of browsing and reading and so on, but because of this story—which broke when I was a freshman—I also spent a good amount of time just staring at the ceiling:
In the fall of 1991, employees at the Maine State Library in Augusta wondered if there was a ghost among the aisles. Odd things, like flashlights, extension cords, and food from the break room refrigerator (mainly pudding cups), were disappearing on a daily basis. At first, security thought the culprits could be some of the workers hired to remove asbestos from the building. But their suspicions changed when, overnight, two refrigerators and a candy machine were nearly cleaned out, and a handwritten note of apology was left behind. As the thefts continued without any signs of a break-in, it became clear that someone was living in the library.
It's so appealing to the Claudia Kincaid in me.
*AHAHAHAHAHAHA, just kidding.