After the destruction of their home planet Thundera, the titular ThunderCats fly off to a new home, only to crash land on Third Earth after being shot down by their arch-enemies, the Mutants. Following a scuffle with the Mutants, Lion-O pursues them into the wild while the rest of the ThunderCats meet the Berbils whose village their ship unknowingly destroyed in the crash. Luckily, the Berbils are quick builders and opt to build their base while warning them of Mumm-Ra. Lion-O ends up encountering Mumm-Ra when chased by the Mutants to the villain's pyramid, with Mumm-Ra destroying the Mutants' ship before returning to his lair.
Lion-O enters the pyramid to thank Mumm-Ra, only to learn he is evil while revealing the presence of the other Thundercats on Third Earth. Mumm-Ra, explaining his Doomstaff grants him power while establishing a curse where anyone who says his name is struck by lightning, chains Lion-O up and uses a portal to attack the ThunderCats' new home. Mumm-Ra makes short work of the team despite their resistance, with Lion-O and Snarf arriving too late. Things seemed hopeless until Mumm-Ra unintentionally praised the Berbils as they hug him with his own curse used against him, enabling the ThunderCats to break free with Lion-O destroying Mumm-Ra's staff. Mumm-Ra, reverted to his natural form, escapes and Lion-O promises to stay with his team and lead them to victory.
Lion-O has gotten a hold of the last jar of Thundersnaps, the best cookies Thundera had to offer! But a difficult to open cookie jar is gonna send Lion-O and Cheetara chasing down a legend, a Boggy Ben-related legend.
Lion-O wants to prove to the ThunderKittens that he's not just some boring old adult, like Tygra, even if it means ignoring his instincts and messing with an obviously evil crystal.
Panthro is getting a little fed up with having to fix things around the Cats' Lair constantly, which is unfortunate because the ThunderCats are about to be attacked by an unstoppable drilling robot, and he's gonna break everything!
A crying unicorn appears at the Cats' Lair and weepily tells the ThunderCats that all of her unicorn friends have been captured! Tygra thinks he's just the unicorn expert to help the last of the unicorns, he just needs her to stop sobbing long enough to tell him who took her friends. Easier said than done.
Vultureman has got a brand new invention but there's one big problem: he stole the idea from Panthro! Oh, also Vultureman is using his invention to take over Third Earth. So, there are two big problems.
Third Earth is being overrun by super tough, super buff Warrior Maidens and it looks like the ThunderCats are next on their hit list! It's gonna be up to the ThunderKittens to save the day even though the kittens are so small and the Warrior Maidens are so big.
Lion-O is reminded that he needs to plug the Sword of Omens into the Cats' Lair each night or else the base will run out of power. That's fine, it's not like Lion-O's going to accidentally lose the sword or anything. Right?
Tygra takes Lion-O climbing up the peak of Hook Mountain to teach him a lesson about trust. But when they get trapped by a snowstorm and take refuge in a creepy cabin owned by the creepy Snowman - it's Tygra's ability to the trust that's gonna be tested.
Tygra's feeling unappreciated by the other ThunderCats so he starts hanging out with Mumm-Ra and cleaning his Black Pyramid?! Whaaaaaaat?
After losing a race to Monkian over who gets to be leader of a local village, Cheetara becomes a successful business person. However, the other Thundercats discover Monkian cheated by drinking a super-speed potion. Now, with the help of Cheetara's biggest fan, Jan-Jan, they need to dethrone Monkian from his seat of power.
Lion-O "accidentally" releases a whole space prison full of criminals and winds up on the wrong side of the law.
Lion-O is tasked with mapping the beaches of Third Earth, which leads to him somehow draining the oceans of all their water entirely.
Lion-O never pays attention during Tygra's training sessions! So when he's asked to do a pop quiz on "sword magic", he accidentally opens a portal to the Astral Plane and releases the Nether Witch on Third Earth.
Every time Mumm-Ra gets ahold of a magic artifact to restore his powers, the ThunderCats just smash it and turn him into a dinky skeleton again. Until today that is, because Mumm-Ra just remembered he's got the Ancient Spirits of Evil on his side.
When the Cats' Lair is attacked by gold-loving robot pirates, Lion-O and the ThunderKittens ditch their chores to fight the robo-pirates.
Jaga, the ghost of the ThunderCats' mentor, visits the Cats' Lair after being freed from the Astral Plane and explains why their home world of Thundera exploded.
While flying with his new invention, Panthro hits it off with new friend Barbastella, the Queen of the Bats.
After a battle with the Mutants, Jackalman gets confused and accidentally returns to the Cats' Lair with the Thundercats.
The Thundercats are exhausted from fighting bad guys all the time so Lion-O suggests they spend a relaxing summer fun day at the beach, with no fighting! Unfortunately the beach is home to the Crabmen, giant, clawed humanoids that fight anyone who steps on their sand! Looks like summer fun day might involve some fighting!
While minding her own business, Cheetara is caught in a trap set by Safari Joe, the famously annoying hunter! After escaping, she rallies the other ThunderCats to help her stop Joe once and for all, by turning the tables and capturing him!
The ThunderCats have gotten so good at defeating the Mutants of Plun-Darr that it's basically become routine. That all changes with the arrival of the Mutants' old leader: Ratar-O, wielder of the Sword of Plun-Darr! Uh-oh!
Lion-O is happily playing with Snarf in their "Frolicking Field" and doesn't have a care in the world, unfortunately he's accidentally stomping all over the miniature village of the Micrits! The tiny people want to defeat the "giant orange monster" but such a quest would require a brave hero. Luckily, the Micrits have such a hero: Prince Starling! Now, let us the tell you the epic tale of Prince Starling as he journeys to find the fountain of growth and defeat the wicked Lion-O, who has no idea any of this is going on!
Lion-O and the other ThunderCats are thrilled to meet a brand new Thunderian: Lion-S! She's cool, good at fighting robots and, most importantly, thinks Lion-O and his Sword of Omens are really neat and interesting! Looks like the ThunderCats have a new best friend! Maybe even, a new ThunderCat?????
Snarf leaves the Cats' Lair to get a needed vacation by transforming into a normal cat and hanging out with a nice old lady on a farm! But his relaxing day is threatened.
The Thundercats' worst nightmare comes true when their worst enemies, Mumm-Ra and The Mutants, team up after Mumm-Ra acquires The Sword of Plun-Darr!
Chaos reigns over Third Earth now that the Mutants and Mumm-Ra control the Cats' Lair! The Thundercats' only hope is to sneak back in and get a super secret weapon Panthro has hidden at the heart of the Lair.
Tygra creates a bunch of new laws for Third Earth so Mandora can finally arrest the Mutants. Unfortunately the Thundercats are really bad at following their own rules and the Mutants are really good at working around them.
When a crate containing fifty Swords of Omen lands on Third Earth, the ThunderCats rush out in the ThunderTank to find them. Unfortunately The Mutants and Mumm-Ra want those swords too so it's going to be a race to get to them! A wacky race, you might say. We won't say that, but you might.
The Cheetara Corp employee retreat gets canceled when Baron Karnor, a mysterious corporate raider, buys them out! Now Cheetara and Jan-Jan must brave the wilds of Third Earth's most dangerous jungles to find the Baron's office and demand a meeting with the man who stole their company!
While on a super important mission to get batteries for the TV remote Lion-O meets Hachiman, a cool Samurai warrior. Now Lion-O will do anything to prove he's just as cool as Hachiman, even if it means risking his own life!
The Thunderkittens plug a new video game cartridge into Snarf only to learn that it didn't load a game, it loaded a whole new personality into their pal! Meet Schnorp, a kind Swedish man who loves the beauty of nature and collecting berries! Schnorp is loads of fun, but we're gonna want Snarf back, right?
The ThunderCats finally sit the Berbils down and tell them they really shouldn't be building things for the Mutants anymore, it's time for the Berbils to stand up for themselves. The Berbils take this advice way too far and build a giant, building-sized, Berbil named Berbcules. Berb-cules takes back everything the Berbils ever built for the Mutants and everything they ever built for the ThunderCats! Now Panthro has to figure out a way to a defeat the most powerful invention the best little builders have ever built!
Mumm-Ra plans to disguise himself as a Thunderian and infiltrate Cats' Lair, but the Ancient Spirits of Evil are mad at him and won't give him any magic today. No matter, Mumm-Ra knows what a ThunderCat looks like so he slaps on some awful, unconvincing, cat make up and heads to Cats' Lair to introduce himself!
Panthro gets insecure when he finds out Barbastella has a history of dating royalty, so he tries to impress her by becoming "King of the Machines" and giving all the appliances in the Cats' Lair artificial intelligence.
When a local sword shop sells an ultra powerful sword to Ratar-O, Lion-O decides he has to steal it before Ratar-O can come pick it up; unfortunately, Lion-O is against stealing.
Lion-O's dad King Claudus arrives on Third Earth, and turns out to be a big selfish jerk! Now Lion-O has to deal with his dad before he goes to war with the rest of the Thundercats.
In order to save the Berbils, Cheetara uses her psychic powers to project a telethon into the brains of everyone on Third Earth.
Mumm-Ra builds a mall that's actually a giant labyrinth designed to trap the Thundercats forever. Too bad the Thundercats love the mall so much they could literally spend all eternity there.
Third Earth's sun is being blocked out by the Eclipsor Corporation, an amoral company that wants to sell its energy for a profit. The ThunderCats can't do anything about it because they don't have a spaceship, yet!
The ThunderCats freak out when a spooky ghost dressed like a pharaoh appears in their mirrors! They quickly set about to getting rid of every reflective surface in their lair, because that ghost is scary and no one wants to talk to him!
The Thundercats agree to foster a demonic puppy from the Astral Plane until they can find it the perfect owner. But could the perfect owner be their worst enemy? Their worst enemy is Mumm-Ra in case you forgot!
The Thunderkittens unleash a demon who is powered by fear. Too bad he's small and not that scary.
The Thundercats invite a super cool swamp man into the Cat's Lair who is on the run from some scary looking aliens!
Tygra says he's done being a Thundercat after he gets engaged to a sentient flower. Now it's up to Lion-O to break up the wedding!
The new rulers of Plun-Darr say they'll bring one of the Mutants home; whichever one of them activates a homing beacon that will blow up the Thundercats. Now it's every Mutant for themselves as they battle it out to be the one to activate the beacon!
The Mutants refuse to celebrate their favorite holiday, Plunds-Mas, now that Plun-Darr is gone. So now it's up to the Thundercats to raise their spirits by enacting the eight horrors of Plunds-Mas!
Mumm-Ra, the Ever-Living decides he'll nap for a thousand years, till the Thundercats are long gone. But when he wakes up, he's shocked to discover that Third Earth is even more in love with them than ever.
The ThunderCats face the greatest threat of their lives: Grune the Destroyer! He's the ghost of an evil ThunderCat and he wants revenge! How are They Gonna Beat Grune??? You'll have to watch the episode!
Tygra is furious after the other Thundercats eat the last of his Thunderian ingredients. To make it up to him they go hunting for substitutes on Third Earth to show him the food on their new planet is just as delicious as the food they had back on their old home.
Santa Claus is on the run from Mandora! Can the Thundercats help him get off Third Earth without getting caught? And can Santa Claus teach them a little something about this weird new holiday "Christmas"?
Meet Lion-O and the Thundercats! After fleeing their home planet, the Thundercats find themselves stranded on Third Earth where they face the evil Mumm-Ra. But Lion-O is strong! He's tough! There's nothing he can't do! Except maybe open really big jars of cookies…
The Thundercats have met their match with the evil, undead Mumm-ra! He and the bumbling Mutants have made it their goal to stop the Thundercats by any means necessary, but of course the Thundercats have other plans!
Cheetara is the coolest cat around! Not only is she so fast that she can outrun lightning, but so clever she can outsmart Mumm-Ra's evil plans! Villains don't stand a chance against Cheetara…well, unless Mumm-Ra uses his Doom Staff, then she might be in trouble.
Panthro may be the strongest cat on Third Earth, but one of his biggest strengths is that he can fix anything! And the rest of the Thundercats break enough stuff to really put his skills to the test, but it's nothing a pro like Panthro can't handle.
The smartest Thundercat, Tygra. Tygra's mission is to make Lion-O a better leader. He might get around to it too, if he wasn't so busy cleaning up after the other Thundercats.
The Thunderkittens might be the youngest Thundercats, but Wilykit and Wilykat are a dynamic brother and sister duo! They'll help take down any foe, even if they don't really know what their own capsule weapons can do.
