The Soul Robber is Jack Skellington's weapon from the videogame: The Nightmare Before Christmas: Oogie's Revenge. It was created by Dr. Finkelstein and given to Jack. When Oogie Boogie is revived, Jack uses it to fight off enemies.
The Soul Robber is a green slime that can change shape when Jack uses it. It is also a living creature that wraps around his arm like a gauntlet.