The BEST episodes of ThunderCats

Every episode of ThunderCats ever, ranked from best to worst by thousands of votes from fans of the show. The best episodes of ThunderCats!

The inhabitants of the planet Thundera evacuate just before it is destroyed. They were pursued by a band of mutants. All but one of their escape ships was destroyed. Only a small group of Thunderans (Thundercats) remained. With only half engine power, the group, which was led by Jaga, had to set a course for the nearest planet. Jaga commanded their ship while the other seven were in their stasis tubes. Jaga died on their journey to Third Earth and their ship crashed there. Soon they made friends with various groups in the area and they designed a fortress. Mumm-Ra the centuries-old embodiment of evil, along with the mutants that destroyed the rest of the Thunderans are a constant threat. But Lion-O, the new leader of the Thundercats, with his weapon the "Sword of Omens" will help the Thundercats to have a standing chance.

Last Updated: 5/8/2024Network: Status: Ended
The Trouble with ThunderKittens
73 votes

#1 - The Trouble with ThunderKittens

Season 1 - Episode 62 - Aired 12/17/1985

The Thunderkittens steal the Thundercats' weapons so they can prove they can use them, but the Mutants steal the weapons! Lion-O and the kittens must get the weapons back from the Mutants.

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559 votes

#2 - Exodus

Season 1 - Episode 1 - Aired 1/23/1985

With their home planet, Thundera, about to explode, the Thunderians flee to a distant galaxy. Before they can make the long journey the Mutants sweep in and destroy most of the fleet in an attempt to capture the Eye of Thundera. Due to the attack, the Thundercats find themselves on a distant planet. A grown-up Lion-O must save his Thundercats from the Mutants on Third Earth.

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The Unholy Alliance
332 votes

#3 - The Unholy Alliance

Season 1 - Episode 2 - Aired 1/23/1985

The Mutants, who have also reached Third Earth, encounter an old pyramid. It turns out to be the home of Mumm-Ra the Ever-Living, and they join forces to capture the Sword of Omens. Both the Mutants and Mumm-Ra attempt to attack Lion-O to possess the Sword, but miserably fail.

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Lion-O's Anointment Final Day: The Trial of Evil
80 votes

#4 - Lion-O's Anointment Final Day: The Trial of Evil

Season 1 - Episode 61 - Aired 12/16/1985

Finally, to prove that Lion-O is worthy to be the Lord of the Thundercats, he must defeat his worst enemy. Mumm-Ra. He manages to find a way into Mumm-Ra's tomb, and defeats him by throwing his coffin into the evil cauldrum. This is the first time that Lion-O really defeats Mumm-Ra.

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139 votes

#5 - Pumm-Ra

Season 1 - Episode 5 - Aired 9/13/1985

Mumm-Ra uses his shapeshifting abilities to pass himself off as a Thunderian so he can stage the "rescue" of Cheetara and infiltrate Cats' Lair.

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Fond Memories
79 votes

#6 - Fond Memories

Season 1 - Episode 65 - Aired 12/20/1985

Mumm-Ra pretending to be one of the ThunderCats friends takes Lion-O to a gallery of the ThunderCats accomplishments. However, the pictures can come to life and Lion-O must battle Rataro, Safari Joe, and others. Once the other ThunderCats arrive they end up in trouble and Lion-O is confronted by Mumm-Ra who has made himself into a carbon copy of Lion-O.

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The Terror of Hammerhand
186 votes

#7 - The Terror of Hammerhand

Season 1 - Episode 6 - Aired 9/16/1985

When Snarf and a young unicorn are captured by the pirate Hammerhand and his crew of Berserkers, Lion-O goes to rescue them.

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The Slaves of Castle Plun-Darr
159 votes

#8 - The Slaves of Castle Plun-Darr

Season 1 - Episode 4 - Aired 9/12/1985

The homeless Mutants also make plans to build their home. They enslave a primitive race of beings called Brute-Men to do their work for them. The Thundercats go to Castle Plunn-Darr to free the Brute-Men from the Mutants.

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195 votes

#9 - Berbils

Season 1 - Episode 3 - Aired 9/11/1985

The Ro-Bear Berbils are a friendly group of robot bears that live on Third Earth. Lion-O and Snarf don't know this, and end up getting caught in a Ro-Bear trap. The Berbils free them however, and they form an alliance. Mumm-ra attacks the Berbil village, but the Thundercats save it. In return, the Ro-Bears help the Thundercats to build Cats' Lair, a new base for the Thundercats.

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The Telepathy Beam
75 votes

#10 - The Telepathy Beam

Season 3 - Episode 9 - Aired 9/15/1988

Vultureman creates a device that plays around with Cheetara's sixth sense. She begins to see images that aren't real, and she soon begins to lose faith in herself. Meanwhile, the Lunataks enslave Panthro with a mind control device, and tell him to make the Sky-Tomb able to fly to Thundera. When the Thundercats are looking for Panthro, Vultureman makes Cheetara see images of him being captured by Mumm-Ra, being stuck on Hook Mt., and being held at Castle Plundarr. Lion-O goes to Mumm-Ra's pyramid, and is ambushed by Luna and Amok, who capture him. Tygra goes to Plundarr and is captured by Red Eye. The Thunderkittens also get captured on Hook Mountain. Cheetara is about to go crazy, but Lynx-O tells her to listen to her heart instead of her mind. She turns into a huge ball of energy that shoots out and destroys Vultureman's device and frees Panthro and the other Thundercats.

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Trouble with Time
123 votes

#11 - Trouble with Time

Season 1 - Episode 7 - Aired 9/17/1985

With their supply of Thundrillium running low, the Thundercats set off in search of a fresh supply. Tygra detects a large deposit in a cave and goes to investigate - unfortunately, he has entered the Cave of Time and anyone who ventures in there will age rapidly until they die. His only hope is that Cheetara's speed will be fast enough to allow her to escape the Cave's effects.

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The Book of Omens
56 votes

#12 - The Book of Omens

Season 4 - Episode 20 - Aired 9/29/1989

New Thundera is being torn apart and the Thundercats must present certain artifacts at various dangerous locations that used to be beautiful places, then Lion-O must go into the book and give the Key of Thundera to the guardian of the book ""at the 24th hour,"" or the Thundercats will be frozen in time and New Thundera will be destroyed. But Mumm-Ra steals the book and key and journeys into the book himself. He wants to save New Thundera BUT wants the Thundercats frozen in time. The Ancient Spirits of Evil try to stop Mumm-Ra because they fear if Mumm-Ra goes into the book, their powers will cease to exist. The other Thundercats run into problems also at the locations they are supposed to be at. Lion-O goes into the book using the Sword of Omens and battles Mumm-Ra one on one, neither of them using any magic. Even when Mumm-Ra cheats, Lion-O still wins. The ASOE summon their ""champion,"" Pyron, to then fight Lion-O, but Lion-O gets the dragons in the book to fry him... He presents the key

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Mumm-Ra Lives! (1)
68 votes

#13 - Mumm-Ra Lives! (1)

Season 2 - Episode 1 - Aired 9/7/1987

The Thundercats think that they have destroyed Mumm-Ra for good. Little do they know that he survived. He returns to his tomb with the help of Ma-Mutt, and is to weak to do anything. So he transforms Ma-Mutt into an image of himself, and sends this image to order the mutants to release the Luna-tacks.

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The Time Capsule
78 votes

#14 - The Time Capsule

Season 1 - Episode 15 - Aired 9/27/1985

Lion-O becomes homesick, and his memories of Thundera are almost nonexistent. Jaga appears to Lion-O and tells him that on their spaceship, they brought with them a time capsule which contained a recording of Thundera and its history up to the time it was destroyed. The Thundercats set out to search for their time capsule.

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The Ghost Warrior
104 votes

#15 - The Ghost Warrior

Season 1 - Episode 11 - Aired 9/23/1985

Two Bolkins (sheep-like beings from Third Earth) unleash the ghost of Grune the Destroyer, a renegade Thundercat who once terrorised Third Earth and now turns his attention to the Thundercats.

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74 votes

#16 - Excalibur

Season 1 - Episode 51 - Aired 12/2/1985

The Ancient spirits of evil show Mumm-Ra the story of King Arthur, and explain to him that the strongest sword that ever existed was Excalibur, Arthur's weapon. Mumm-Ra disguises himself as Arthur, and returns to lake where the sword is guarded by the lady of the lake. Fooled by his disguise, the lady gives Mumm-Ra Excalibur. The disguised Mumm-Ra challenges Lion-O to a dual, and Lion-O foolishly accepts the challenge. The sword clash, and Excalibur is victorious. The eye of Thundera is split in two, and the Thundercats become powerless. Merlin, Arthur's teacher and a famous magician stops Mumm-Ra from destroying the Thundercats, and restores the eye to its original state.

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Lion-O's Anointment Third Day: The Trial of Cunning
54 votes

#17 - Lion-O's Anointment Third Day: The Trial of Cunning

Season 1 - Episode 46 - Aired 11/25/1985

Wily Kit and Kat stand in Lion-O's way on the third day of his trials. Lion-O must beat them through the maze of infinity. Attempting to stop Lion-O and slow him down, the kids set traps in the maze. He manages however to avoid their traps. In order to beat them through the maze, Lion-O plays their own tricks on them, and tricks them into losing the race through the maze.

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Lion-O's Anointment Fourth Day: The Trial of Mind Power
53 votes

#18 - Lion-O's Anointment Fourth Day: The Trial of Mind Power

Season 1 - Episode 50 - Aired 11/29/1985

The scene changes to Hook Mountain, where Lion-O must beat Tygra at a test of mind power. The Tiger Clan on Thundera were given special mind powers that enable them to produce illusions to their enemies. Lion-O must be able to distinctly separate the real from the unreal. Lion-O is clever enough to see past Tygra's illusions, and is able to earn his Thundercat insignia during day four of his trials.

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Key to Thundera
49 votes

#19 - Key to Thundera

Season 3 - Episode 11 - Aired 9/19/1988

While trying to figure out a way to read the Book of Omens, Lion-O tries looking through the sword at the book. He is immediately drawn into the book, where a voice asks him if he has ""the key."" Lion-O says he doesn't, and four dragon heads appear and shoot fire at him. Snarf, who saw Lion-O get sucked into the book, tries to show Cheetara what happened, and he too gets sucked in. Mumm-Ra, who also watched Lion-O get sucked in, goes to cats lair and takes the book so he can destroy it with Lion-O inside. Meanwhile, just by coincidence, Panthro finds an odd looking key on Thundera. He and Tygra head back to Third Earth with the key, not knowing what it's for. Back on Third Earth, Mumm-Ra is just about to boil the book when Lion-O calls for the sword, and it brings him and Snarf back outside. Mumm-Ra takes the sword and looks through it at the book, and he gets sucked in! But Lion-O has to save him because of the code of Thundera, and Lion-O does save him. Panthro and Tygra arrive with t

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Return of the ThunderCubs
50 votes

#20 - Return of the ThunderCubs

Season 3 - Episode 12 - Aired 9/20/1988

Panthro, Tygra, and Cheetara return to New Thundera in the Feliner to find more of the Treasure of Thundera, but Mumm-Ra shoots the Feliner down and, as the Fog of Despair, sends them to the Canyons of Youth, which changes them back into Thundercubs. Then Mumm-Ra disguises himself as Lion-O and tells the Thundercubs to find the treasure for him. Meanwhile, back on Third Earth, Lion-O and Snarf decide to go rescue the Thundercats on New Thundera, but they must ask the Mutants to take them to New Thundera in the Rat-Star. The Mutants agree, secretly planning to attack Lion-O once they're in space. They do attack and imprison him and Snarf on the way to Thundera, but they manage to break out. Cheetara meanwhile, using her sixth sense, locates part of the treasure, the Mirror of Truth. The real Lion-O shows up, and uses the Sword of Omens with the Mirror of Truth to restore the cubs to their proper age, and Mumm-Ra reveals himself and turns into Mumm-Ra the everliving. Cheetara uses the mi

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Return to Thundera! (5)
52 votes

#21 - Return to Thundera! (5)

Season 4 - Episode 5 - Aired 9/8/1989

After another earthquake caused by Mumm-Ra ruins the new Cats Lair construction site, the Thundercats go to see Jaguara and confront Mumm-Ra. Unfortunately, Mumm-Ra puts up a force field over entrance. Jaga appears to Lion-O and tells him to use the Eye of Thundera to get to Jaguara and the Gyroscope. Lion-O does so and battles Mumm-Ra, who throws him into the bottomless pit underneath the Gyroscope. Lion-O however, manages to throw his grappling hook to the top, which pulls him back up. Lion-O then shines the signal, which goes through the force field. All the Thundercats leap through the signal which takes them through the force field. Together, they fire all their weapons at Mumm-Ra and he is defeated. But before he leaves, he breaks the cord that holds the Gyroscope above the pit and it falls through. Now, New Thundera is literally falling apart. But Lion-O throws the sword in the spot where the Gyroscope used to be and calls upon the Thundercat Ancestors for help. The sword starts

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The Zaxx Factor
47 votes

#22 - The Zaxx Factor

Season 4 - Episode 18 - Aired 9/27/1989

Vultureman escapes from exile by hijacking a bookmobile. He finds a disk containing ancient history about two powerful evil forces on Third Earth: Mumm-Ra and his enemy Zaxx. Zaxx used a Rosencrest medallion, but Zaxx was defeated when Mumm-Ra stole the medalion trapping Zaxx in it. Vultureman plots to get the medalion, defeat Mumm-Ra, and rule the universe. So Zaxx uses Vultureman to find and defeat Mumm-Ra. But there's a terrible ""side effect"" to the medalion, anyone who wears it loses his own life and BECOMES Zaxx. When Vultureman learns of this, he changes his mind. The Thundercats get caught in this situation when Vultureman attacks Panthro and Snarf and after they crash, Snarf dissappears. Zaxx then uses Snarf to attack Mumm-Ra and Zaxx takes over Snarf's body. The other Thundercats arrive and save Snarf. Mumm-Ra defeats Zaxx once more by takin the medalion, but the pyramid also collapses on Mumm-Ra.

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The Spaceship Beneath the Sands
90 votes

#23 - The Spaceship Beneath the Sands

Season 1 - Episode 14 - Aired 9/26/1985

Tired of constantly being bested by the Thundercats, the Mutants have Mumm-Ra raise their spaceship and salvage their vehicles.

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Mumm-Ra Lives! (3)
54 votes

#24 - Mumm-Ra Lives! (3)

Season 2 - Episode 3 - Aired 9/9/1987

The Luna-tacks build their fortress with the help of the brute men. They call it Sky-Tomb, and not only is it powerful, but it can travel through the air. It is a mobile fortress. The Thundercats ask the Berbils to help them build a new structure called the Tower of Omens, that would help them easily locate the position of Sky Tomb, and stop the Luna-tacks as fast as possible.

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Return to Thundera! (1)
64 votes

#25 - Return to Thundera! (1)

Season 4 - Episode 1 - Aired 9/4/1989

The Ancient Spirits of Evil give new life to Mumm-Ra and Ma-Mutt, send them to New Thundera, and build a new Pyramid for Mumm-Ra. The Thundercats say goodbye to Third Earth and depart for Thundera, leaving Tygra and Pumyra behind to watch Cat's Lair and the Tower of Omens. The Thundercats soon arrive and begin plans to build a new lair. Mumm-Ra meanwhile learns that the planet's gravity is controled by the Gyroscope under the Churning Rocks at the center of the planet. The Gyroscope is guarded by Jaguara, an ancient Thundercat sorceress. Mumm-Ra disguises himself as Jaga and puts Jaguara under a spell, making her change the rotation of the Gyroscope to throw the Thundercats clear off the planet. As the Thundercats are floating away, Lion-O calls on the Eye of Thundera to help him, and it breaks Mumm-Ra's spell... but not before Mumm-Ra takes part of the Gyroscope's regulator. Without those controls, the planet will be destroyed within 2 hours...

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