The chief villain and antagonist against the ThunderCats, the demon-priest Mumm-Ra is the self-proclaimed "ever-living source of evil" on Third Earth, having powers of sorcery and an apparently unlimited lifespan. He is, in fact, a bound servant to the Ancient Spirits of Evil (represented by four anthropomorphic statues within the burial chamber of his pyramid), who provide him with increased power and virtual immortality to further his pursuit of spreading their dark influence throughout Third Earth.