Red is a ruthless and sadistic demon who enjoys destroying worlds and tormenting victims without mercy. His cruelty even drives his own follower, Solomon, to betray him. Obsessed with control, Red quickly eliminates any threat to his dominance.

Acacius is a golden humanoid with 3 star-shaped spikes on his back and a head that resembles a knight's helmet. Although not mentioned in the story, Acacius belongs to a species known as the 'Agelums', a race of divine golem-like beings whose purpose is to uphold and enforce certain 'rules' the game maintains. Some of these aforementioned rules were broken by Red across the story, and it can be assumed that this is what caused Acacius to appear and intervene.

Solomon is a large, blue demonic humanoid with red eyes, sharp teeth, bat-like wings, and bird-like claws on his legs. His body is covered in blue fur. After he is brought back by Melissa, his eyes turn blue.

Godzilla was Zachary's starting monster, along with Mothra, and notably his favorite that he used most frequently. As the game progresses, Godzilla is regularly used by Zach, up until the Quiz Level in Entropy, where Face removes him, alongside all other playable monsters but Mothra, from Zach's control. He is later regained in Extus.

Anguirus is an Ankylosaur who has horns similar to those of a Styracosaurus, a spiky shell on his back, and the tail of a crocodile. He can adopt both a bipedal and a quadrupedal stance, like Baragon.