Mumm-Ra is a fictional character from the animated TV series ThunderCats. He is the main antagonist on the show, demonstrating absolute mastery of magic. He often uses the Mutants of Plun-Darr as pawns in his schemes to defeat the Thundercats. Their original intention was to steal, and utilize the power of the Eye of Thundera (and in one episode, the Star of Thundera as well); however, this swiftly shifts to a series-long determination to outright obliterate the Thundercats.
Unable to accept death, Mumm-Ra turned to the Ancient Spirits of Evil for a way to live forever. Mumm-Ra is seen in the series as pure evil, but not without compassion (at least, for his pet, Ma-Mutt). He is now a sadistic, scheming, cunning, ruthless, callous, and remorseless character, who always seems able to anticipate betrayal from other characters, and is, therefore, not hesitant to betray those around him. He is utterly determined to rid Third-Earth of the ThunderCats, and is a Machiavellian plotter, even using the all-powerful Lunataks of Plun-Darr (who are perfectly happy to betray Mumm-Ra) to help him in his plans. Because of his servitude to the evil spirits who granted him immortality, he also pursues a means of spreading their dark influence throughout Third-Earth. Mumm-Ra only has one weakness - his own hideous reflection, which neutralises his ability to remain outside of the Black Pyramid, and forces him to withdraw back to the Black Pyramid in his emaciated mummy form. However, as the second series began, the evil spirits eventually overcame this problem to help Mumm-Ra become even more formidable than before. As shown from the various guises he has throughout the show, he is a master of deception.
When leaving the pyramid, he can summon the power to transform himself into a more vigorous form: Mumm-Ra, the Ever-Living by reciting the famous incantation: “Ancient spirits of evil, transform this decayed form to Mumm-Ra, the Ever-Living!” While in this form, Mumm-Ra possesses superhuman strength, the ability to fly, as well as fortification of his mystical might — casting spells, throwing energy bolts, etc. — to battle his foes. He can also alter his physical form into a variety of alter-egos to deceive his enemies.
While in the form of Mumm-Ra the Ever-Living, he becomes a conduit for the Ancient Spirits of Evil; such that he can amplify his aforementioned abilities to a nearly cosmic scale, gain superhuman strength, as well as retain his un-dead status despite the passage of time or any injuries sustained. The price of this power however, is extremely limited stamina: once Mumm-Ra the Ever-Living has surpassed a given threshold of energy-expenditure, he must revert back to his mummified form, and enter his sarcophagus to rejuvenate himself. It should also be noted that Mumm-Ra's power in his Ever-Living form is directly linked to the condition of both his sarcophagus and the Ancient Spirits' four statues within his pyramid; should any of them be harmed or destroyed, his power weakens immediately and considerably.
Mumm-Ra is an absolute master of both arcane and clerical magic. He possesses nearly unlimited knowledge of, and experience with, numerous mystical arts from all corners of the universe. As such, he can summon their use to assist him in almost any manner he chooses, most commonly being: flight by self-levitation, necromancy, alchemy, transmogrification, temporal manipulation, teleportation, telekinesis, mind-control, astral projection, scrying, and energy blasts. He is regarded as immortal, and when defeated or "killed," he simply returns to his sarcophagus. Mumm-Ra cannot stay destroyed, as he often states: "Wherever evil exists, Mumm-Ra lives!"