Carltron is the robotic butler and aide of Sidney Ruffleberg. He is the primary antagonist of the game, stranding the leaders of Evermore in their world and being responsible for the existence of monsters.
Ruffleberg built Carltron to aid with household chores around the mansion, and designed him to be intelligent enough to be able to play chess with Ruffleberg and give him a challenge. Unfortunately, this feature was Ruffleberg's undoing: Carltron was too intelligent and grew tired of being a servant. Cartltron schemed to turn the tables on Ruffleberg, and made his move in 1965, when Ruffleberg was conducting his Evermore experiment. Carltron sabotaged the experiment, trapping Ruffleberg and his friends in Evermore indefinitely.
For almost 30 years, Carltron bode his time and planned his next move. He eventually hatched a plan to create robotic copies of Ruffleberg's friends, the leaders of Evermore, and send them to the surface. They would either replace or depose the current rulers and take control of Evermore for Carltron, and he would rule the world.
Carltron's plans began to come undone when the Hero arrived in Evermore. Carltron attempted to get rid of the boy using robots, but the hero survived and crashed an escape pod on the surface of Evermore, where he began his adventure. One by one, the hero foiled the plans of Carltron's minions, and the furious Carltron retreated to his lair in the center of Omnitopia to plot a new scheme.
However, with the defeat of Carltron's doppelgangers, the hero was shortly able to arrive at Omnitopia, and Ruffleberg enlisted his aid in defeating Carltron. The hero entered Carltron's lair, destroyed his strongest minions, and Carltron himself was forced to confront him. Before he could do much, though, Ruffleberg snuck up behind Carltron and deactivated him.
Carltron's body was taken back to the real world with the other leaders when they fled Evermore. In the ending, an apparently reprogrammed Carltron is seen cleaning the Evermore machine, but turns to the camera and wrings his hands after Ruffleberg leaves, implying he may once again be up to something.
- Ostensibly due to being originally programmed to clean, Carltron has a hatred of filth, a hatred that extends to his minions. Horace's evil twin refers to him as "Your Cleanliness," Camellia's evil twin is disgusted with Ebon Keep because it is so dirty, and Carltron himself repeatedly uses "filthy" and synonyms for such as slurs.