Unfinished business in the past leads to undead creatures bothering the present. That’s your average phantom for you. They’re pretty unsettling until you realise what they’re trying to tell you. Then, like an unfinished Corrective Action, laying them is a simple task.
Our favourite phantom movie: The Haunting, because it does what it says on the tin. Or maybe Ghost, because the early 90s haunt us still.