Morg is the main antagonist of the episode Billy and Mandy vs The Martains. He is the Martian Grim Reaper. It's a magical alien skeleton works as the death of the planet Mars, a planet he also rules as the evil emperor of the zombies on the planet. His obsession is to take over swaths of the deaths of the solar system to dominate the universe with great supernatural power.
To begin the first phase of its plan of conquest, Morg does appear disguised as a human to Grim, Billy and Mandy to inform the latter that the agreement that the three came in the game of limbo that took place long ago would only be valid on Earth, so giving your card to Grim, proposes to leave the Earth to be free. Grim accepts heading towards Mars spacecraft Morg, where he reveals his identity and posing as the death of Emperor Mars, beginning a friendship between the two deaths. Later, Morg encourage Grim decides to join him in his plan to rule the Earth, using as support the fact that Billy and Mandy make fun of him for not dominate anything, thus convincing Grim. That's when Morg and Grim prepare to conquer Earth with his ejécito, goal finally achieved.
After that, Morg begins the second phase of his plan, find a human with a stupid mind with which to control the zombies of planet Earth through stupid thoughts. It then begins to try Morg Brain-Caster with several residents of Endsville to find the perfect subject, but not succeed, and tired of Skull tell him that Billy is the ideal subject for your plan proposes to Grim Morg go for a game for fun, but then discovers the room where the ashes and Morg had swaths of the other deaths. Morg then tells Grim that were broken by accident, and that he was better than the other deaths, earning back the trust of terrestrial death.
Later, Morg discovered that Billy, Mandy and Irwin, who believed swallowed, seek to stop him, so Morg sends his zombies to capture and bring Billy to put on the Brain-Caster while sending Mandy and Irwin into a pit with a dangerous creature. Later, seeing Grim rectified and helps Mandy, Morg decides he no longer needed, sending the inhabitants of zombified Endsville against them. However, Billy's stupidity affects the zombies too distracted by that. In an attempt to solve the problem, Morg accidentally breaks the Brain-Caster, returning to normal Earth and freeing Billy.
Finally, Mandy, Grim and the Admiral Wolverine Lightningbolt cornering to Morg, who tells Skull to always be at the service of Billy and Mandy, which states Skull prefer to be with him. Mandy then proposes to convert Morg, Grim in his own servant, but Billy presses a button that launches Morg into space. Finally, Morg swears revenge while wandering through space before fleeing into a vortex.
- The name, 'Morg', is just the word 'Grim' spelled backwards, the 'i' replaced by an 'o'.
- It is also phonetically identical to "morgue", the area of a hospital where corpses are kept.