In their ongoing mission to spread the Code of Thundera, and in their efforts to build homes for themselves on Third Earth and New Thundera, the ThunderCats must face evil in many forms. From ancient enemies from the planet Plun-Darr to the ever-living devil priest Mumm-Ra, the ThunderCats must fight to protect themselves and their friends from ever-present evil.

The true embodiment of evil on Third Earth and an enemy of many guises, Mumm-Ra will stop at nothing until the Eye of Thundera is in his clutches and the ThunderCats have been completely destroyed!

From the planet Plun-Darr comes the threat of the fearsome Mutants, who have pursued the ThunderCats from Thundera to Third Earth in their quest for the Eye of Thundera. Bringing together the most powerful warriors from the differing Mutant races, the ThunderCats strive to keep the Mutants' evil at bay.

Evil creatures from the moons of Planet Plun-Darr, and from beyond the wildest imagination, the Lunataks pose a threat like no other.

With a new world comes new dangers! As the ThunderCats strive to build a home for themselves, they come up against many hostile beings native to their adopted planet, beings who will stop at nothing to eradicate beings they see as intruders!

The ThunderCats' galaxy-spanning adventures bring them into contact with many enemies from across the universe - from bounty hunters and mercenaries to aliens of all description, all equal danger for the ThunderCats.

As the Thundercats explore Third Earth and beyond, they discover a number of unique and dangerous creatures.