Origin
A creature developed by Morty from the Rickless Universe for the sole purpose of killing Rick Sanchez.
Creation
Written by Zac Gorman and drawn by CJ Cannon.
Major Story Arcs
The Goo Monster leaves the Rickless Universe via the dying powers of a portal gun. It arrives in a parallel universe and violently kills its fun-loving Rick. The Goo Monster is apparently able to move through universes, as it follows the dead-Rick’s Morty and kills him, too. It is not known what happens to the Goo Monster at this.