[13] 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.

When the ThunderCats awaken from their suspended animation on Third Earth after ten "galacto-years", Lion-O discovers that his suspension capsule has slowed, rather than stopped, his aging.

The intrusion of these two alien races upon the world does not go unnoticed, however, as a demonic, mummified sorcerer calling himself Mumm-Ra recruits the Mutants to aid him in his campaign to acquire the Eye of Thundera and destroy the ThunderCats so that his evil may continue to hold sway over Third Earth.

[14] The basic plot above sets the stage the first season of the show, and serves as the basis for stories mixing elements of science fiction and fantasy into a traditional good-versus-evil tale, introducing recurring allies and villains into the world of the ThunderCats.

Each episode would normally include a short dénouement, featuring the characters recuperating after the events of the story and taking the time to single out a personal value or wholesome approach that helped save the day, or could have done so if they had seen it.

The other ThunderCats were each then forced to involve themselves in the conflict specifically to foil the Mutants' interferences—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 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.

Earl Hammond (Mumm-Ra and Jaga) and Bob McFadden (Snarf and Slythe) would most regularly provide the voices of guest characters.

It was rumored to be an original story expanding on the events of the first episode and the film's concept artwork (released in July 2009) contained the main character Lion-O and three locations.

[32] Despite an early positive response (with the animation in particular receiving heavy praise from critics), the series failed to make any real impact and viewing figures slowly declined after the first episode, with blame falling on a relatively dark and complicated storyline considering the show was aimed at 6-12 year olds.

[34] Beginning in 2002 ThunderCats titles were published by Wildstorm Productions, an imprint of DC Comics (Warner Bros.' corporate sibling), and included 5 non-canon mini-series and several one-shots.

PVC companions were packaged with some figures in 1986, including WilyKat with Tygra, WilyKit with Cheetara, Snarf with Lion-O, and Ma-Mutt with Mumm-Ra.

LJN did produce a few variant figures including the young Tygra version and the silver rat-eye daggers for Rataro.

An unproduced final series of figures would have included The Mad Bubbler, Red-Eye of the Lunataks, Ratilla, Cannon-Blaster and Quick-Jaws from the Bezerkers as well as the Feliner, Thunderstrike and Luna Tacker.

Other ThunderCats merchandise of the 1980s included, among other items, a board game, TV tray table, an electronic racing set, tin lunch box, clothing and apparel.

In May 2009, Warner Brothers gave Hard Hero the rights to produce a line of collectible statues based on the ThunderCats characters.

[40] In February 2011, Mezco Toyz acquired the ThunderCats license to produce large scale rotocast figures based on the 1980s animated series.

Jerry Macaluso, owner of Pop Culture Shock, collectible statue company, announced in March 2010 that he had acquired his "dream license".

Prototypes of Cheetara and Tygra were developed and displayed online and at San Diego Comic-Con, respectively, but did not reach minimum pre-order thresholds.