Lloyd
I have yet to read the book, having only seen the film, but what is up with Lloyd the bartender?
Jack had already begun to lose his mind by the time we meet Lloyd, but up to this moment, Jack hadn't (at least on screen) interacted with any other phantoms, let alone know them by name and interact with them.
Taking into consideration the hotel feeding off Jacks' psyche, I'm just curious if perhaps Jack knew Lloyd somewhere else in the world before working at the Overlook, which is why he didn't flip out and run when a ghostly bartender with fully stocked shelf magically appears.