ThunderCats was created by Tobin “Ted” Wolf and animated by Japanese animation studio, Pacific Animation Corporation. The original series ran from 1985 to 1989 (130 episodes).
The show follows the adventures of the Thundercats – catlike humanoid aliens on a planet called Third Earth. The series plot begins with the dying planet Thundera meeting its end, forcing the ThunderCats (a sort of Thunderean nobility) to flee their homeworld. The fleet is attacked by the Thundereans’ enemies, the Mutants of Plun-Darr, who destroy most of the starships in the “ThunderFleet,” but spare the flagship hoping to capture the legendary mystic Sword of Omens they believe is on board. The sword holds the Eye of Thundera, the source of the ThunderCats’ power, which is embedded in the hilt.
Though the Mutants damage the flagship, the power of the Eye drives them back. The damage to the ship means the journey to their original destination is not possible, instead having to journey to “Third Earth”; which will take much longer than they had anticipated. The eldest of the ThunderCats, Jaga, volunteers to pilot the ship while the others sleep in capsules; however, he dies of old age in the process, but not before ensuring they will reach their destination safely. The flagship contains the young Lord of the ThunderCats, Lion-O, as well as the ThunderCats Cheetara, Panthro, Tygra, WilyKit and WilyKat, and Snarf.
- “Day One: The Trial Of Strength” – Lion-O had to defeat Panthro in a strength contest.
- “Day Two: The Trial Of Speed” – Lion-O had to beat Cheetara in a race.
- “Day Three: The Trial Of Cunning” – Lion-O had to outwit both of the WilyKat and WilyKit in an underground location.
- “Day Four: The Trial Of Mind-Power” – Lion-O was pitted him against Tygra in a mind-based challenge
- “Last Day: The Trial Of Evil” – Lion-O had to defeat Mumm-Ra. Lion-O discovered that Mumm-Ra was highly dependent on the sarcophagus inside which he had been mummified.
On all four days except the last, the Mutants tried to interfere with Lion-O’s trials so that they could force the ThunderCats to remain leaderless. The other ThunderCats were then forced to involve themselves in the conflict to foil the Mutants’s interference—all while trying to avoid assisting Lion-O in his anointment trials.
Although intended to be viewed consecutively (as the adventures depicted occurred one day after the other), the five parts of the mini-series were erroneously aired (and released on DVD) with multiple other episodes between each installment.
In 1986 the Thundercats brought out the TV movie ThunderCats – Ho! written by Leonard Starr. It featured the first major shake-up to the status quo of the series, introducing three new Thundereans (whom Lion-O later anointed as ThunderCats) who had also survived the destruction of Thundera. A massive cast of returning heroes and villains were incorporated into the story and concluded with the apparent destruction of Mumm-Ra.
When the series returned in 1986 for Season 2, it was revealed that the evil wizard Mumm-Ra had survived. Mumm-Ra Lives! set the pattern for the following three seasons, which each began with a five-part mini-series, again written by Leonard Starr, that established the new characters and concepts that would go on to influence the rest of the season.
In the case of “Mumm-Ra Lives!”, these concepts included the debut of the villainous Lunataks, who became a third faction that existed for the rest of the series, and the new team of Thundercats from ThunderCats – Ho! being given their own headquarters, vehicles and so forth.
Season 3 (1988) opens with the Peter Lawrence-scripted ThunderCubs, which, though named for its plot about the Thundercats being transformed into children, was principally about Mumm-Ra reconstructing Thundera in order to retrieve both the weapon that had originally destroyed it (the Sword of Plun-Darr) and the legendary Treasure of Thundera.
In the course of the adventure, the treasure—containing the Book of Omens, a tome holding all the secrets of the ThunderCats, and many other mystical items—was scattered across the New Thundera, ushering in a new concept for the series: a season with an actual story arc. Continuity between episodes became tighter as the ThunderCats, Mutants, Lunataks and Mumm-Ra alternated their adventures between Third Earth and New Thundera, searching for the treasure and exploiting its powers. The season also featured the running theme of the Ancient Spirits of Evil having to take a more active hand in pushing Mumm-Ra into action, culminating in another unique feature of the season—an actual finale episode, The Last Day, in which the Ancient Spirits of Evil give Mumm-Ra one last chance to destroy the Thundercats by sunset. Besides demonstrating their threat by making Ma-Mutt disappear, the Ancient Spirits of Evil stated that Mumm-Ra’s failure will also have the Mutants and the Lunataks removed from Third Earth as well. Ultimately, Mumm-Ra failed and the Ancient Spirits of Evil exiled him to the farthest corner of the Universe.
In the opening miniseries to Season 4, Return to Thundera! (written by Peter Lawrence) the Thundercats returned to New Thundera to rebuild their society, but before departing, they destroyed Mumm-Ra’s pyramid. This enraged the Ancient Spirits of Evil to the point that they brought Mumm-Ra back and installed him within a new pyramid on New Thundera. The season proved to be quite divorced from what had gone before, with adventures consigned almost entirely to New Thundera, and most villainous opposition coming from either Mumm-Ra or assorted new villains. The Mutants, Lunataks, and Captain Cracker all returned for one episode each, however.
In the series finale, several conclusions are reached including Mumm-Ra standing up to and successfully asserts himself over the Ancient Spirits of Evil, the mystery of the Book of Omens was at last solved and the tumultuous and terrifying environment of Thundera was at last rendered peaceful and pristine.