When the world of Happy Tree Friends transported to earth, the tree friends meet a nice girl called Jen-Jen who can save the day. But the only characters that were with Jen-Jen are Cuddles, Giggles, and Lumpy, as the rest are missing from Evil Flippy's outrage, turning them into gigantic monsters. Only Jen-Jen and her friends can rescue them if they battle them, complete missions, and transform. Each episode is 22 minutes long.
- Jen-Jen: A 13 year old girl who found Cuddles, Giggles, and Lumpy and must find the others.
- Cuddles: A yellow rabbit who has a crush on Giggles. His battle forms are Shockles and Cudzap.
- Giggles: A pink chipmunk who has a crush on Cuddles. Her battle forms are Gigflaze and Kaboomgles.
- Lumpy: A dim-witted blue moose. He hates to be with Evil Flippy and he goes with Cuddles and Giggles. His battle forms are Lumpcheese and Lumpzilla.
- Disco Bear: A yellow bear. He's a disco dancer, but Evil Flippy orders him to rampage by making him eating junk food and turn into a monster. His battle forms are Disferno Bear and Disfunk Bear.
- Flaky: A red porcupine whose quills are full of dandruff. Evil Flippy orders her to rampage by playing baseball and turn into a monster. Her battle forms are Clawky and Drillky.
- Handy: An orange builder beaver. Evil Flippy orders him to rampage by eating nothing but Jen-Jen's birthday cake, then turn into a monster. His battle forms are Metalhand and IronHand.
- The Mole: A purple blind mole. Evil Flippy orders him to rampage only if Jen-Jen attacks him, causing him to turn into a monster. His battle forms are Hauntmole and Molreaper.
- Mime: A purple deer. Evil Flippy orders him to rampage by going in a dark place, then turn into a monster. His battle forms are Mimeread and MasterMime.
- Petunia: A blue skunk who wears a car air freshener. Evil Flippy orders her to rampage by turning everyone into plants, then turns herself into a monster. Her battle forms are Plantuia and Pollenia.
- Pop and Cub: Tan bears. Cub is the smaller one and Pop is the bigger one. Evil Flippy orders them to rampage by putting all kinds of scary and funny things somewhere, then turn into monsters. Pop's battle forms are Poprotect and Popaw. Cub's battle forms are Cubbear and Grizzbear.
- Toothy: A purple beaver. Evil Flippy orders him to rampage by faking his own death, then turn into a monster. His battle forms are PunchTooth and SumoTooth.
- Sniffles: A nerdy blue-gray anteater. Evil Flippy orders him to rampage by winning the Smart-o-Tron, then turn into a monster. His battle forms are Nerffles and Dr. Sniff.
- Lifty & Shifty: Twin raccoons. Evil Flippy orders them to rampage by doing all the tasks given, then turn into monsters. They later betray him to join Jen-Jen and the gang after the events of Out of Control. Lifty's battle forms are Yinlift and Liftsassin. Shifty's battle forms are Shifyang and Mafiashft.
- Clumsy: A gray raccoon who has an arrow on his forehead. Evil Flippy orders him to rampage by attacking Jen-Jen's town as a monster.
- Flippy: A green bear who served in a war. Flippy dosen't flip out in the show because his evil self is a now seperate being. Flippy was the first one to be captured by Evil Flippy, who was planning to kill him, Sneaky and Mouse Ka-Boom, but the gang rescued the three after defeating Evil Flippy in combat. His battle forms are FlipKill and ChaosFlip.
- Sneaky: A green soldier Chameleon. Evil Flippy captured him, Flippy and Mouse Ka-Boom and planned to kill them.
- Mouse Ka-Boom: A orange mouse with explosives. Evil Flippy captured him, Sneaky and Flippy and planned to kill them.
- Evil Flippy: A green bear who's a evil version of Flippy and the one who made all the tree friends (apart from Cuddles, Giggles, Lumpy, Flippy, Sneaky, Mouse Ka-Boom, Fresko, Munchkins, Jingles, Russell, Cro-Marmot, Neena, Tacho, Buddhist Monkey, Panda Mom, Truffles, Tricksy, Rudy and Splendid) go with him.
- Nutty: A green squirrel who loves candy. Nutty didn't appear in the first season but appeared in the second season. Evil Flippy orders him to kidnap the other tree friends and turn himself into a monster. His battle forms are Nutleaf and Nuttree.
- Lammy: A purple sheep/lamb who has a friend called Mr. Pickels. Lammy didn't appear in the first season, but appeared in the second season. Evil Flippy orders her to go with Nutty in order to kidnap other tree friends and turn herself into a monster. Her battle forms are Lamfrost and Tundralam.
- Coach Z: A green hyena with a yellow and pink sailor outfit and purple hair. Coach Z didn't appear in the first season but she appeared in the second season. She saved Nutty and Lammy and turned them back to normal.
- Russell: A blue-green sea otter with typical pirate accessories. Russell made a cameo appearance on Fun and Games in the first season, but appeared in the second season. Russell and Cro-Marmot managed to escape Evil Flippy before he could capture them. His batlle forms are Russmatey and CaptinRuss.
- Splendid: A blue flying squirrel and a rival of Splendont. Splendid only appeared once in the first season, but appeared fully in the second season. Splendid went through the same door Cuddles, Giggles and Lumpy went though to stop Evil Flippy. His battle forms are Splenbird and Splenhorus.
- Buddhist Monkey: A monkey who is calm and kind most of the time. Buddhist Monkey didn't appear on the first season but appeared on the second season. Buddhist Monkey, Tricksy, Rudy and Truffles came to the tree friends' aid when Frankenette attacked. His battle forms are Buddhist Yinyang and Buddhist Master.
- Panda Mom: a female panda who carries her baby around in a cradleboard.
- Cro-Marmot: A prehistoric marmot from the stone age. Cro-Marmot didn't appear on the first season but appeared on the second season. Cro-Marmot and Russell managed to escape Evil Flippy before he could capture them. His battle forms are Ice-Marmot and Tundra-Marmot.
- Neena: A light blue cat that has long brown hair, wears magenta glasses, light blue outfit and blue pants. Neena didn't appear in the first season but appeared in the second season. Neena and Tacho appeared when the gang found Russell and Cro-Marmot. Her battle forms are Neeice and Snowna.
- Tacho: A red wolf with dandruff on his hair and tail, much like Flaky, Tacho didn't appear in the first season but appeared in the second season. Tacho and Neena appeared when the gang found Russell and Cro-Marmot.
- Truffles: A blue sailor pig. Truffles didn't appear in the first season but appeared in the second season. Truffles, Rudy, Tricksy and Buddhist Monkey came to the tree friends' aid when Frankenette attacked.
- Tricksy: A ferret with a knack for pranks and all kinds of practical jokes, Tricksy didn't appear in the first season but appeared in the second season. Tricksy, Rudy, Truffles and Buddhist Monkey came to the tree friends' aid when Frankenette attacked.
- Rudy: A purple ram dressed in a kung fu costume, Rudy didn't appear in the first season but appeared in the second season. Rudy, Tricksy, Buddhist Monkey and Truffles came to the tree friend's aid when Frankenette attacked.
- Fresko: A light blue cat. Fresko, Munchkins and Jingles came to help the tree friends when Evil Flippy attacked Jen-Jen's town. His battle forms are Freskool and Freskrush.
- Munchkins: A black cat. Munchkins, Fresko and Jingles came to help the tree friends when Evil Flippy attacked Jen-Jen's town.
- Jingles: A yellow chipmunk. Jingles, Munchkins and Fresko came to help the tree friends when Evil Flippy attacked Jen-Jen's town. Her battle forms are Psygles and Jesteringles.
- Splendont: Another villain character. He's a red flying squirrel. He's also a rival of Splendid.
- The Rat: The third villain character. He's a spy rat. He always want to grasp the mask first. He hates The Mole.
- Tiger General: The forth villain character. He's a blue tiger. He is also Flippy's enemy.
- Char Sui: The fifth villain character. He's a pink pig warrior. He's is also Buddhist Monkey's enemy.
Buddhist Monkey, Tricksy, Cro-Marmot, Panda Mom, Splendid, Truffles, Rudy, Russell, Nutty and Lammy appear in the second season.
- Sir Emily: A posh school girl. She is a rival of Jen-Jen, but in the episode Fun and Games she helped Jen-Jen and the tree friends stop Pop and Cub.
- Ginny and Homer: Jen-Jen's friends. Homer has blonde hair and wants to be cool, while Ginny has black hair and wears red clothing.
- Annie : Jen-Jen's sister. She's 16 years old. She hates Flaky because she thinks that Flaky's going to kill her in the night.
- Toadette: Homer's sister. She's 7 years old.
- Pete: Ginny's older brother. He's 17 years old.
- Rini and Mini: Ginny's twin little sisters. Rini always wears pink clothing, while Mini always wears yellow clothing.
- Raven and Eagle: Sir Emily's parents. Raven is her mother and Eagle is her father. They're rich.
- Violet: Sir Emily's sister. She's 8 years old.
- VJ and Daisy: Some of Sir Emily's friends.
Cuddles, Giggles, and Lumpy are alone in the HTF world and must find a secret door. Once they find it, they end up in the Budeligh town, where they meet Jen-Jen.
The gang spots Disco Bear, but he's stuck in Evil Flippy's curse, as he's eating food all day and turns into a big giant hungry monster.
- Go, Giggles, Go!
The gang goes to a fast food restaurant for Lumpy, but spots Flaky on the way, so Giggles must play baseball for her. During so, she transforms.
It's Jen-Jen's birthday, but Evil Flippy orders Handy to eat the whole birthday cake without asking.
- Fake Up or Truth Up
When Jen-Jen bumped into a famous fighter, she battles the fighter, but hits The Mole by mistake.
There's a dance at the village hall and Mime joins the dance in order to kill Jen-Jen by going for a date in the dark.
- Plant Day
Petunia comes and turns everything into evil plants, but Mime goes alone to battle Petunia.
Something weird is happening to Jen-Jen's place, as it's filled with funny things like balloons, as well as scary things like witches. Pop and Cub are also there.
- Night of the Were-Tree Friend
Handy gets bitten by a werewolf, then turns into a half werewolf while finding out that Toothy's going fake his own death.
- Smarty Pants
The Fun Fair comes to town, featuring the Smart-o-Tron, but Sniffles comes and ruins it.
- Out of Control
Clumsy is attacking Jen-Jen's town. He later becomes a helper, as he doesn't transform.
- Hard Lucky
The gang watches Lifty and Shifty rampaging, so Jen-Jen battles them.
- Crazy Bear
Evil Flippy battles Jen-Jen and the gang, but they better do something or Evil Flippy will kill Sneaky, Mouse Ka-Boom and Flippy.
- Valentine Day
Jen-Jen, Mime, Disco Bear, Petunia, and Giggles go to the Valentine's Day Fair, but Disco Bear goes crazy as he waits for Cuddles.
- Full Power
Evil Flippy has attacked Jen-Jen's town, but the good news is that Fresko, Munchkins and Jingles have come and Cuddles is now in his Cudzap form.
- Tough Love
A group of sexy female rockers that Handy always wanted to see comes to the town, so he wishes that he earns his new form (IronHand). His wish comes true and everyone loves him, but for some reason he's stuck as his IronHand form.
- C-lfen Lied
Jen-Jen and Mime go quad-riding while Cuddles and the rest get lost in a gift shop full of quads. Later, Lifty and Shifty ride a dangeous quad called Projet Chisel, but Fresko, Cuddles and Disco Bear enter the quad race and transform in order to help Jen-Jen and Mime on the way.
- The Incredible Bulk
Evil Flippy turns into a big strong monster, so the gang must stop him before he destroys Jen-Jen's town.
- Ewww... That's Growth!
The Fair comes again, featuring a new, deadly ride, but Disco Bear is too short, so he grows by making himself too tall.
- This is Halloween
It's Halloween at Jen-Jen's Town, but something freaky is going on as the tree friends are transformed into spooky ghosts by Evil Flippy while visiting Halloween town.
- Mombo Jumbo
Evil Flippy turns Jen-Jen into a rabbit, Cuddles into a moose, Lumpy into a chipmunk, Giggles into a beaver, and Handy into a lamp.
- Mid Form Zone
The tree friends get trapped in their mid-forms and enter a zone with Lifty and Shifty.
- Journey to the Center of Handy
Handy swallowed his tools when making Lumpy's new bed, so Lumpy, Toothy, Sniffles and Sneaky go in there to find all the tools.
- Rebel Robot Ranch
Sniffles, Toothy, Handy, Disco Bear, and Cuddles pretend to be space outlaws and fight robots, while Lifty and Shifty transform into S.H.R. (Super Hyper Robots).
- Ginny in Wonderland
Ginny falls down a rabbit's hole and it seems that it was Cuddles who did it, so the gang must find her.
Season 2 (Fighters Collide)
Lammy and Nutty invade Jen-Jen's town as giants. What can the gang do?
- Armor Mode
The gang find Cro-Marmot and Russell, Meet Neena and Tacho and can finally armor with Lammy, Nutty, Cub, Disco Bear, and Pop. Meanwhile, Tiger General, Splendont, The Rat and Char Sui have just entered Evil Flippy's lair.
- The Tattletale of The Monster Frankenette
The gang has a camp in the woods, but The Rat tries to call out the scariest monster in the world, Frankenette, that Buddhist Monkey, Panda Mom, Tricksy, Rudy and Truffles find.
- Big in Time
Jen-Jen travels to the time when no one found Cuddles, Giggles, and Lumpy in the first place and went on a rampage which no one can't stop, until Splendid returns from the HTF world.
Sir Emily was injured after a fighting traning, then finds a short clone of herself, and tries to make everyone funny while Splendont turns into a monster.
- Sugar Sweet
Rini and Mini want Ginny to work at a candy factory which makes the tree friends fatten up.
- The Time of Mime (Part 1)
After saving a child from a flash flood caused by Char Sui, Mime thinks he saw his other forms travelling through time.
- The Time of Mime (Part 2)
All 3 Mimes travel 5 years into the future, revealing Jen-Jen as a worker, Sir Emily as a queen, Homer is fat, and Ginny gets married to Disco Bear.
- The Time of Mime (Part 3)
The 3 Mimes get stuck in a game and they must find a way home.
Disco Bear takes an experimental treatment that transforms him into a giant blob to take revenge on Splendont. Disco Bear squeezes out of Jen-Jen's house and wreaks havoc on Jen-Jen's town, only for Handy, Russell and Mime save the day.
- Clown Hater
Mime never hates clowns, but what about Pop and Cub?
- Cheerleader Blues
Jingles, Neena, Giggles, Petunia, Lammy, and Flaky join Jen-Jen's cheerleader squad, but The Rat and Splendont come to join, dressing up as girls.
- Can Aliens Control Your Mind?
Sir Emily tries to trick Jen-Jen to think aliens are real, so Sir Emily builds a rocket ship to Mars and infects Jen-Jen with a virus. An alien witch then takes over all the tree frends' minds. Sir Emily and Violet then go to Mars together to save Jen-Jen from an alien curse.
- Transform but really Big
After Homer messed up Jen-Jen's helmet, the tree friends transform but grow unusually big as well.
The gang heads towards a snowy place, but Giggles gets kidnapped by The Rat. It's revealed that she was saved by a strong man called Bluestar.
- Pepper Cat the Movie
Giggles takes a roll of Pepper Cat the Movie while Petunia sets up a party, but trouble seems to go too far and she ends up transforming.
Ginny and Homer form a band, but end up captured by the government.
- Panic 2: The Startling
The gang is being attacked by giant ants.
- Rise of Dark Bear
Splendont uses the power of darkness to supercharge Evil Flippy.
- The 10 Power Squares
The gang finds out how to beat Splendont. They have to find the 10 power squares.
- Supers of Them All
Dark Bear battles the gang, while Splendont, The Rat, Tiger General and Char Sui plan their final assult.
- Battle to the Face
The gang return Evil Flippy to normal and Splendid, Flippy, The Mole and Buddhist Monkey have a chance to battle Splendont, The Rat, Tiger General and Char Sui.
- Another Confrontation
The rest of the gang plans to destroy Evil Flippy once and for all.
Season 3 (Healers Collide)
In this new season, Ginny's hair has grown longer and the story involves the gang finding all 9 masks which were fallen into the wrong hands.
- The Mask of Beast
The gang find the mask of beast, but Tiger General got his paws on it first.
- Powerful Thing
The gang finds the poison mask that Evil Flippy was put on, but The Rat needs it fast and tries to get it off.
- Good Doggy
Violet's pet, Fuzz Beebo, has worn the vore mask. If Beebo keeps growing, she'll eat everyone in town
- Caterpillar Craze
The hunger mask that Pete put on turns everyone into caterpillars.
- Halloween in the Fight
It's Halloween and the fighter mask hits Homer, causing him to fight Pete.
Mini eats a part of a mask, which makes her age goes on fast.
- Half Together
After spliting the mask in half, Flippy and Flaky put the halves of the mask together.
- Back Again
Jen-Jen returns to town to buy something, which is a mask, but Char Sui puts it on.
- Heck No!
The gang finds out a tunnel that hides the final mask. Meanwhile, Coach Z upgrades her transformation.
- Trouble in Big Park
As the Gang enters a theme park, Splendont makes a shadow of Jen-Jen come to life.
- Rise of The Nega Tree Friends
Evil Flippy creates evil clones of The Tree Friends to take out Jen-jen and the gang, but they rebel against him and plot their own plan to take over the world.
- Flippy Claus is Coming to Town
Splendont and The Rat have kidnapped Santa Claus, thus the spirit of Christmas and the New Year have gone away, so Flippy, Lifty, Shifty, and the long-awaited return of Bluestar go to save Christmas before it is too late.
- The Return of Frankenette
Tiger General and Char Sui bring Frankenette back to life and the gang must team up with Bluestar to stop Frankenette's rampaging.
- Imaginary Land
Violet goes in her very own imagination land, but she seems that she is stuck in there, so Jen-Jen and the gang have to save her.
- The Revenge of The Nega Tree Friends
The Nega Tree Friends return to get revenge on the gang, so they must team with unlikly ally, Frankenette.
- The Final Battle
The Dark Shadow Lord is tired of Evil Flippy's repeated failares so he invades Jen-Jen's town and shrould the world in darkness, So Jen-Jen, her family and friends, The Tree Friends, Bluestar, Frankenette, Evil Flippy, Splendont, The Rat, Tiger General, Char Sui, the Nega Tree Friends and even Sir Emily and Violet must team up to save the world and stop The Dark Shadow Lord.
- Happy Tree Friends Partners Collide: The Movie
- Happy Tree Friends Partners Collide 2: Evil Flippy's Revenge
- Jen-Jen's, Ginny's, and Homer's parents never appear. Sir Emily's parents are the only ones that appear.
- For the very first time, the tree friends can finally talk in clear English.
- This show has a little bit of deaths.
- Jen-Jen makes a cameo appearance in Zombiepalooza! in Happy Tree Friends: Worlds Collide!. She's shown fighting off zombie Flaky.
- The transformations are based on Skooterwolf's HTF Pokemon artworks.
- Truffles, Buddhist Monkey, Panda Mom, Cro-Marmot, Neena, Tricksy, Rudy, Tacho, Splendid, Russell, Lammy, Nutty, and Coach Z appear in the second season.