Had another evil monster-ish idea.

The hangman is an evil spirit born when someone is executed for a crime they did not commit and have great hate toward that fact. They are forced to become that crime, being partly in hell but since they did not truely committhe act, they can't fully be there, they possess a human by wrapping them in their noose tongue. After long enough exposure, the human will go on a killing rampage, which condemns their soul and the remainder of the hangman to hell.