Maoh is very demonic looking, with his entire body colored brown, hued orange, and covered in spikes. In the Overworld, Maoh appears to have no eyes, although in the Underworld they glow a bright red color. His face is on his chest area and he wears a crown of spikes. His arms start above his head because of the placement of his face. Maoh has a membrane that runs from his lower body up to his elbow much like one of his creations, Hotter. He also has scaly legs ending with clawed feet.
Maoh was the fifty-third kaiju to battle Greenman. He is the source of all evil in the world, and was banished to the Underworld by God. To be freed from the underground prison, Maoh must collect the blood of human children, but his plans usually devolve into pure mischief, and attempts to stop Greenman. He has a sidekick named Tonchiki and clay doll servants called the Minions of Maoh which both are tasked by Maoh to collect the blood.
Maoh is first seen in Episode 1, Greenman vs. Garamedon, seemingly suffering from amnesia after being banished to the Underworld, but Tonchiki reminds him of what he has to do to be freed from the prison, and Maoh soon returns to his scheming ways, intent on achieving his plans.
After all but one of his minions are destroyed by Greenman, he teleports to the surface to get the blood himself. However, he is unable to move his legs because of his banishment. Using a magic spell, he transforms some of the children into stone, and summons Tonchiki to take the stones to the underworld.
Greenman fights him, but Maoh quickly retaliates, utilizing dark magic to stop Greenman in his tracks. However, the remaining children use their Green Calls to free Greenman from the magic. Now fully recharged, Greenman went to the underworld and used his Greenman Stick ability to free the Children. He then went back to the surface and engaged Maoh once again, and killed him with his Flash Shock.
- Maoh, using an unnamed power, can place energy into clay dolls and turn them into his minions.
- Maoh can see everything Tonchiki and Tonchiki's monsters are doing.
- Maoh can teleport out of the Underworld despite the fact that he is banished there, however, he can not move his legs when outside.
- Maoh is weak to electricty, and was instantly killed when Greenman used his Flash Shock attack on him.
- Maoh is one of a small amount of monsters in the series that have not grown to giant size.