Prometheon is a giant artifical creature that was released on Earth, trying to absorb all of its heat but was defeated by Superman in Superman: The Animated Series. It was voiced by Frank Welker.
The creature was once artificially created by an alien race to do manual work and was powered by the planet's two suns but later went out of control and went on a rampage. They were able to capture the creature and placed it on an asteroid where it can't absorb heat, rendering it in an inactive state.
Arrival on Earth
Later on, the asteroid headed for Earth and Superman investigated the asteroid and found Prometheon. The military launched a missile at the asteroid, freeing Prometheon who began its search for a heat source. The creature first absorbed heat from a nuclear reactor that was used in a submarine. Prometheon reached the surface where military General Hardcastle launches missiles at the creature in hopes of destroy it. Instead, the explosions of the missiles provided the creature with more heat to absorb. Prometheon later decided to ventured to Metropolis to absorb more heat.
The creature began absorbing heat from a steel mill. Superman fought the creature which proved to be a difficult encounter until all power from the city has been shut off. Unfortunately, Prometheon absorbed heat from the moon until Superman distracted it by setting a boat containing gas on fire. Prometheon turned its attention towards the boat and goes into the lake until two chemical compounds made from S.T.A.R labs were dropped into the lake, freezing the creature. It is unknown what became of the creature afterwards.