Thundercats is a 2013 American action adventure comedy film written and directed by James Gunn starring Matt Damon, Hugh Jackman, Natalie Portman, Vin Diesel, Thomas Brodie-Sangster, Emma Watson, Seth MacFarlane, Ron Perlman, Andy Serkis, Dwayne Johnson, Ian McKellen and Liam Neeson.
Thundercats narrates the story of the thunderians, sentient beings with a cat-like appearence that once resided in the utopy planet of Thundera. However, one of their own, Grune (Johnson) betrays the Thunderians in exchange of military power by the Mutants led by Slythe (Serkis). Few survive, and are composed with the sons of the King Claudus (Neeson), Lion-O (Garfield) and Tygra (Jackman), alongside Panthro (Diesel), Cheetara (Portman) and orphans WillyKit (Watson) and WiliKat (Sangster). They must now reclaim a new land and stop the evil being know as Mumm-Ra (Perlman) who allied himself with Slythe and Grune in attempt to conquer the few remaining planets in the galaxy.
- Matt Damon as Lion-O: the leader and the hereditary "Lord of the ThunderCats." Lion-O, based on the lion, wields the legendary Sword of Omens, which is able to fire bolts of energy and allows Lion-O to see across great distances with its power of "Sight Beyond Sight", as well as the Claw Shield, a gauntlet that launches grappling lines from its claws. A mere child of twelve years old at the time of Thundera's destruction, Lion-O aged to adulthood during the trip to Third Earth when his suspension capsule failed to prevent him from aging too much. Although cunning and skillful, he is truly a child in a man's body, and throughout the film, must learn what it takes to become a true leader and gain true maturity.
- Hugh Jackman as Tygra: The adopted older brother of Lion-O. A flirtatious ladies man, Tygra possesses extreme xenophobia, a jealous streak, and an inferiority complex. All of which often serve to cause friction between himself and Lion-O. As he would learn later in the film, Tygra is of the Tiger Clan who were forced to live far from Thundera due to their continued loyalty to Mumm-Ra even after his entrapment. Sent to Thundera as a baby by his biological father Javan, Tygra was raised by Claudus and his wife with the latter loving Tygra dearly prior to her death while giving birth to Lion-O. Losing both the right to succeed his foster father and the only mother he knew, Tygra grew to hate Lion-O and questioning the latter's decisions after he became the new Lord of the ThunderCats. Furthermore, Tygra fell in love with Cheetara when they first met as children in the past, although he believed she never returned his feelings for her. Her apparent friendship with Lion-O gave him another reason to bear a grudge on his brother. Tygra and Cheetara eventually become a couple after confessing their feelings for each other in the ending's climax.
- Natalie Portman as Cheetara: One of the last remaining cleric warriors. When she originally tried to join the Order of Clerics as a child, she was initially turned down by Jaga, because even though she had the speed possessed by clerics, she lacked the patience. Despite being turned down, Cheetara decided to show Jaga she had the patience needed to become a cleric, and began to wait in front of the Order's doors. While waiting, she was given a flower by Tygra, which helped Cheetara sustain herself, until Jaga finally allowed her to join the clerics. In the aftermath of Thundera's downfall, Cheetara's possibly the sole surviving member of the Order, other than Jaga, who lives on in spirit form. Cheetara initially served as counselor to Lion-O, since she never shunned him for his interest in technology and initially seems to support his kindness to other races.
- Vin Diesel as Panthro: Panthro is one of Claudus' more loyal soldiers who was sent with his friend Grune to find the Book of Omens. Their attempted search resulted with Mumm-Ra's release and Grune betraying Panthro, who while fighting Grune fell down an abyss and seemingly was killed. However, Panthro survived and constructed the ThunderTank, which he later used to save Lion-O's group from Slythe's platoon. Though he questioned Lion-O's ability to lead, Panthro eventually accepted him as the new king. Unlike the rest of the ThunderCats, he never learned how to swim. In the film's near end, Panthro duels with Grune when he and Slithe attack the Elephants' village against Mumm-Ra's orders. Panthro loses most of his arms while trapping Grune in the astral plane, killing him. He was later outfitted with mechanical arms built by the Berbils which can also elongate themselves. Even though a warrior in all forms of ThunderCats martial arts fighting, Panthro has a brilliant mind, which he uses as the chief mechanic/engineer and pilot for the ThunderCats. He is also physically the strongest and is a cunning warrior in combat, relying as much on martial arts as on physical strength.
- Thomas Sangster and Emma Watson as WilliKat and WilliKit: Twin siblings, Kat being the older brother and Kit as the younger sister where both of them are based on the wildcat; they are jointly referred to as "ThunderKittens" by the other characters, although technically they are older than Lion-O. They are the mischief-makers, and often have their own lessons to learn alongside Lion-O while they live on Third Earth, where they frequently use tricks and traps to combat evil. Kit is the more adventurous, while the older Kat usually errs on the side of caution. Kit also appears to be the more agile, and at times, she employs a rolling-attack against the enemy. They were originally from a middle-class family in the countryside living with their mother, their father, and their two siblings. When the two lost their father to a tornado with the family becoming more down-trodden, the twins resolve to run away from home to find the lost city of El Dara and become rich. However, upon arriving to Thundera, they were forced to become street urchins and lock-picking pickpockets in order to survive the slums with their aspirations the only thing keeping them going. When the Lizards attack Thundera, the two manage to escape during the chaos before eventually teaming up with the ThunderCats on their journey.
- Ian McKellen as Jaga: Jaga served as head of Thundera's cleric warriors, possessing a knowledge of ancient secrets, superhuman speed, projecting lightning from his staff. In his prime, he used the "Sword of Omens" in an epic duel against Slythe. At the start of the film, Jaga sacrifices himself to ensure Lion-O and his group escape. This resulted with him being tortured into revealing the location of the "Book of Omens" to Mumm-Ra, though doing his best to resist the villain's magic when sealed within a lantern, eventually his free will wavers along with his physical form. Though Jaga destroys the lantern that was keeping his soul intact to save Lion-O from Mumm-Ra, his soul took residence within the Book of Omens and becomes Lion-O's guide.
- Ron Perlman as Mumm-Ra:The chief villain and antagonist of 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 servant to the Ancient Spirits of Evil who provide him with increased power and virtual immortality to further his pursuit of spreading their dark influence throughout Third Earth. Residing within the Black Pyramid amid the ruins of what appears to be an ancient Egyptian civilization, Mumm-Ra exists in a decayed, weakened mummified form that must return to a stone sarcophagus to replenish his energy. He can transform himself into a far more vigorous and muscular form - Mumm-Ra, the Ever-Living - by reciting the incantation: "Ancient Spirits of Evil, transform this decayed form... to Mumm-Ra, the Ever-Living!" While in this form, Mumm-Ra possesses 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. Seemingly invincible in whatever form he chooses, Mumm-Ra have a singular weakness: seeing his own hideous reflection neutralizes his ability to remain outside the Black Pyramid and forces him to withdraw there in his emaciated mummy form. However, the Ancient Spirits of Evil revoked this shortcoming. Mumm-Ra is a master of deception, and will use whatever means necessary to fight against the forces of good.
- Andy Serkis as Slythe: The brutish leader of the Reptilians, a race of Lizard Men. Although he lacks sophistication, his intuitive cunning is considerable. Domineering and impatient, Slithe often must browbeat the other reptilians into going along with his plans. He pilots the Nosediver. Slithe served as Rataro's cook earlier in his career, and he retains a discriminating palate.