Created by Atlanteans, Colossus was put in charge of awakening the people of the city, who went into suspended animation to escape a great earthquake. However, during the huge earthquake that sank the city, the robot was damaged and turned evil and kept its own makers in suspended animation. The city rose from the depths in modern times and the monster-like robot awoke. Soon the Calico was drawn into the city by a tractor beam, no doubt activated by the robot. When Godzilla tried to help, he was blasted with a beam of light and taken, allowing the Calico to be destroyed in the city's interior. Looking around, the crew soon found Colossus wandering the streets in search of life to destroy. Knowing they'd need him, they began to search for Godzilla.
When the Colossus blasted a building with its beams, Godzilla was revealed to be in suspended animation. However, Godzooky tricked the robot into firing at Godzilla. The blasts awoke him and Godzilla started fighting Colossus. Godzilla ripped both its arms off, but many more simply replaced it. Knowing his foe was mechanical, Godzilla carried Colossus to the sea. In a single throw the machine was sent into the deep and destroyed by the water. The death of the Colossus woke not just the Atlanteans, but also Quinn and Brock, whom were also trapped in suspended animation. The Atlanteans sent the Calico crew back in time before their ship was destroyed and then retreated into the void of space where they had originally came from.
- Colossus can fire powerful blasts of green energy from its eyes.
- Colossus can extend several arms, all ending in pincers, from each side of its body.
- Colossus can increase its size by extending its upper-body from the lower. It can then shrink back down to size if it needs.
- Colossus will be destroyed if dumped in water.