A person with ninja-like skills who is able to blend into dark areas with ease. He may get pleasure out of hiding from people in said dark areas.
Guy1:Hey,have u seen my brother.
Girl1:No,I have not.
Guy 2 walks out of shadow: You talking about me?
Guy 1 and Girl 1:HOLY CRAP!!! WHERE DID YOU COME FROM?!
Girl 2:You are such a nightshadow.