List of Ben 10 episodes

When school is ready to dismiss for the summer, Ben Tennyson is ready to take a cross country trip with his grandfather, Max Tennyson. Unfortunately for Ben, he learns that his rival cousin, Gwen Tennyson, is along for the ride. Meanwhile, the evil alien Vilgax is attacking an alien transport to retrieve the Omnitrix, a device of incredible power. He succeeds in boarding the ship, but the device is launched in an escape pod and sent to Earth. After arriving at a campground and dealing with Max's strange dinner, Ben wanders out into the forest for a walk. During this, he's nearly struck by the escape pod. When he goes to investigate and finds the Omnitrix stored inside, the Omnitrix jumps onto his wrist, unwilling to come off. Now Ben finds that he can transform into ten powerful aliens, each with a unique ability. This proves to be well-timed, since Vilgax will stop at nothing to retrieve the Omnitrix and sends his robots to procure it for him. With his new powers, Ben is able to stop the robots. Safe for now, Ben, Gwen and Max begin their summer cross country trip.

In Washington D.C., Ben is starting his superhero career by rescuing some people from a burning building by using Heatblast. At the same time, he chases down some jewel thieves. Even though he's gotten the hang of the hero aspect, he still doesn't have the reward part down, since he expects recognition for all that he does. In another part of town, a scientist named Dr. Animo is trying to complete his Transmodulator, a device that can mutate normal animals into giant versions of themselves, as well as reanimate dormant cells, effectively bringing back the dead. The second function of the Transmodulator requires some parts, so he goes to the nearest M-Mart to get them, leading him into Ben. Ben saves the store, but Dr. Animo escapes. The trio pursues Dr. Animo to the Museum of Natural History, where he completes his Transmodulator and reanimates a T-Rex. Despite Ben's efforts, he escapes once again. On top of that, Gwen is kidnapped by Dr. Animo's giant bird. Some insight into Dr. Animo's past reveals that he is chasing after the Verites Award, which he had lost to a Dr. Kelly five years earlier. After saving Gwen, Ben is able to stop Dr. Animo quest for the reward. Seeing some of himself in Dr. Animo, Ben realizes that being a hero can be its own reward.

While camping and swimming at a lakeside campsite, Ben encounters a sea-monster in the lake. Gwen and Max don't believe his claims at first. The next day, they go fishing and meet Captain Shaw, who identifies the sea-monster as the Krakken. Shaw is determined to capture it. They later meet Jonah Melville, who appears to be an animal lover but is nothing of the sort. They soon find out that Jonah has been stealing the Krakken's eggs. The three eventually end up at odds with the Krakken and each other, each with their own intentions towards the creature. Ben is eventually able to stop Jonah and return the creature's eggs, appeasing it and getting Jonah arrested at the same time.

While shopping at an ice cream store in the desert, thieves attempt to steal an ATM. Ben and Max capture the them, but their problems don't end there. They drive to a retirement center to visit Ben's Aunt Vera, but something very strange is happening here. Ben finds out that there is an evil species of alien shape-shifters, called the Limax, kidnapping and replacing the residents in order to devour them later. Now, Ben must save the day without even being sure who the enemy is. They eventually find out that the Limax intend to devour the senior citizens they've kidnapped, and with teamwork they are able to send them home empty-handed.

When Vilgax sends three alien bounty hunters - the crustacean-like Kraab, the mechanical assassin Sixsix, and the mysterious Hoverboard - to recover the Omnitrix, Ben learns that simple brute force is not always the best solution to a situation. He also learns that not everything is as it appears when one of the hunters turns out to be another Petropsapien, like Diamondhead. With some advice from both the unexpected ally and his grandfather, Ben is able to defeat the hunters. The alien leaves Ben with the Omnitrix, saying that it's in good hands for now.

Max takes the kids to Sparksville, a town that gives new meaning to the phrase "tourist trap." After being disappointed with their star attraction, a giant rubber-band ball, Ben changes into Fourarms to play a prank on the lame town. In doing so, he accidentally unleashes Megawhatts, little creatures made from electrical energy. Now he must stop them from multiplying out of control and destroying the town with their dangerous pranks.

In a hotel, Ben spots an area where they are demonstrating a new game. He decides to use Ghostfreak's power to sneak in. He is caught, and Ben, Gwen, and Max are kicked out. After Ben and Max argue, Ben wanders out into the city on his own. There, he meets Kevin, a sociopath who has the power to absorb any form of energy. After Ben is forced to reveal what the Omnitrix is capable of, Kevin suggests that they team up. Once Kevin turns out to be too violent for Ben's tastes, Ben tries to stop him. Kevin then begins absorbing the powers of the Omnitrix for his own benefit. Ben learns that there are sometimes where you can't have everything your way all the time.

Ben, as Fourarms, thwarts an armored car robbery by a very tough female named Joey. During the fight, some of Vilgax's new and improved drones attack and Max is injured. When Fourarms takes Max to the hospital, Joey starts messing with the drones and is converted into a powerful alien cyborg named Rojo. With these enhancements, Vilgax is able to communicate with her and convince her to work for him. When she attacks Ben at the hospital, she is thwarted once again, but Ben is left thinking that it's too dangerous for him to be around others and runs away. During their final confrontation, it turns out to be the advice of Max that helps Ben defeat her. As Upgrade, he is able to stop her, but not before receiving a disturbing message from Vilgax.

After dealing with some criminals at a dock, the trio finds their way to a circus run by a clown named Zombozo, much to Ben's chagrin. There, Ben's fear of clowns comes out as they explore. They find a freak show along the way, featuring a trio of mutants with incredible abilities. During Zombozo's show, Ben is too afraid to laugh and ends up leaving. His departure turns out to be for the best, since Zombozo drains the happiness of others to sustain and empower himself. Meanwhile, Ben finds the freaks robbing the town. Ben is able to beat them, but can't bring himself to fight Zombozo. He has to find a way, though, since Zombozo kidnaps Gwen and leaves the entire town in a chuckling daze.

A magician named Hex, whose powers come from mystical charms, is defeated by Ben using XLR8 and a little help from Gwen and Max. Afterwards, XLR8 takes all the credit for the victory and even gets one of Hex's charms as a souvenir. When Gwen complains that Ben is getting all the glory as well as all the cool stuff, he gives her the charm he got from Hex. The charm gives Gwen perfect luck in everything she does, so she becomes her very own superhero, Lucky Girl. Unfortunately, her luck has a price and Ben is the one who ends up paying it.

When Ben turns out to be too short to ride a water slide, he decides to use Ripjaws to get by the problem. When the Omnitrix won't cooperate, he has to smash it several times to activate it, accidentally ending up as Grey Matter. His problems are just beginning, though. Soon after transforming, he is captured by a man named Howell Wayneright, who is obsessed with finding aliens and hopes to trade him in for fame. Furthermore, Grey Matter is now stranded in this form, an apparent side effect of his rough handling of the Omnitrix. To make matters even worse, Howell decides to turn Grey Matter over to The Organization, a secret society dedicated to collecting alien technology for their own benefit. Now Grey Matter has to escape from both Howell and The Organization, as well as find his family in the process.

When Councilwoman Liang attempts to redevelop the downtown area, demolition efforts draw the wrath of a man named Clancy, who has the power to control insects. Meanwhile, Ben stops a criminal as Upgrade and finds an ice cream truck afterwards. When he climbs inside to get a snack, he gets himself locked inside and ends up with a cold. The virus causes strange side effects in his alien forms, making his normally powerful forms severely weakened. On top of that, Clancy kidnaps the councilwoman and threatens the entire city with a nuclear holocaust. Now Ben must save the day while dealing with the strange side effects in his alien forms.

Now that Vilgax's injuries have fully-healed, he decides to retrieve the Omnitrix personally. Ben learns of Vilgax's imminent arrival through a dream and tells Grandpa Max, who is worried by the revelation. He insists that they get to Mount Rushmore as quickly as possible. With them on the move, Vilgax is unable to pinpoint the exact location of the Omnitrix. Narrowing down the location, he lays waste to a nearby city in order to flush its holder out. He succeeds, despite Grandpa Max's protests, and manages to capture Ben. Grandpa Max continues to Mount Rushmore with Gwen and shows her a huge facility beneath the mountain. There, he's stored a weapon that can defeat Vilgax. Unfortunately, the weapon fails, and now it's Vilgax versus the combined Tennyson family.

After the incident with Vilgax, Max tells Ben and Gwen about his secret past. He really was a plumber, but not the garden variety version. He was part of a secret government organization known as "The Plumbers," that dealt with extra-terrestrial and paranormal phenomenon that others couldn't. The organization was disbanded after he defeated Vilgax for the first time. During one of Ben's regular acts of heroism, they run into Max's old partner, Phil. Phil is still in the business of hunting aliens, though he is now a freelance agent. He suggests that they remake The Plumbers, but Max is against the idea. Ben, however, is much more enthusiastic about the idea. During another alien battle, Ben reveals the secret of the Omnitrix to Phil, and Phil is even more determined to get him as a partner. Phil ends up taking them to an expensive hotel, which he is able to pay for thanks to rewards for capturing the aliens. The frequency of the alien attacks, as well as the familiar aliens themselves, raises Max's suspicions, and he heads to Mount Rushmore to check on something. There, he finds the Null Void Projector – a weapon that can trap things in, or release them from, an alternate dimension – missing. Phil has been using it to scam various hotel owners into paying him to remove the aliens that he sets free. Phil releases an alien to deal with Max, but Ben is able to rescue him and eventually trap Phil in the Null Void Projector.

During a trip to Yellowstone National Park, Ben discovers a new form on the Omnitrix: Cannon Bolt, an armadillo- and beetle-like alien. At the same time, a meteor crashes nearby unleashing a giant, tick-like alien called the "Great One" that intends to devour the planet. On top of that, it has its very own worshippers, who intend to make sure it completes its task. Though the worshippers are easily handled by Ben, the Great One is impervious to all his original alien forms. Since nothing else works, Ben has to rely on a form he knows nothing about in order to defeat the Great One.

In San Francisco, Ben discovers that look-alikes of his aliens are committing crimes around the city. On top of that, a team of government agents known as SACT (Special Alien Capture Team) is trying to capture them. When he confronts one of the imposters, he learns that its Kevin who has been posing as his aliens. Their last battle has permanently given Kevin the ability to transform into the various aliens of the Omnitrix. Unfortunately for Kevin, he can't stay in human form for very long. Understandably upset, Kevin plans to get Ben sent to jail for the crimes he commits. Now Ben has to stop Kevin while avoiding the SACT team in the process.

When Ben wakes up one morning, he finds the Omnitrix missing from his arm. Weirder still is the fact that Gwen and Grandpa Max have no idea what he's talking about when asked about it. Ben soon discovers that he's actually reliving the very first day of summer, the same day that Ben found the Omnitrix to begin with. At the campsite, Ben tries to find the Omnitrix as it crashes to Earth, only to find out that it has already been found... by Gwen! While Gwen quickly adjusts to the Omnitrix's powers (with much greater skill than Ben), Vilgax is already heading for Earth to take it back from her, preferably in a very painful way. Ben's going to have to prove himself to be a hero without the Omnitrix to back him up if he wants to save Gwen.

Out in the middle of nowhere, Ben, as Diamondhead, is locked in a fight with Kevin, who is still in his mutated form. As they fight, a teleportation beam takes them to a huge ship called the Mega Cruiser, where life or death gladiator matches are regularly held between slaves captured from different alien races. But when the ship's owner, a mechanical droid named Slix Vigma, decides to create a bond with Ben and Kevin as a team, they immediately turn his idea down. But with no choice, they must find a way out. Will Ben and Kevin learn the importance of teamwork?

When a pair of bounty hunters plan to use raw minerals from earth to build a devastatingly powerful bomb, Ben joins a group of alien super heroes, the Galactic Enforcers, in order to stop them. However, all is not well with the new group, as a small gift of Ben's chocolate is all that's needed to weaken the group's leader, Ultimos. This causes his second, Cynaptak, to take the lead in order to try showing Ben up. However, the Enforcers tactics involving 'commanding presence' backfire on them, and nearly getting Tiny hurt in the process. However, after Ben goades Cynaptak into rescuing Tiny from a landslide, Ben and the Enforcers put aside their differences to finally arrest the bounty hunters.

When Ben and Gwen argue over a birthday party to occur in the next few months, Max is distracted by their quarreling and almost hits a young boy camper. They take they boy back to his camp, Camp Opinicon, only to find no one there. As they investigate the premises, they find two more children, twins, who are hiding from something that caused the camp to become deserted. When they try to leave, Max finds that the RV's engine has clogged with fungus. During a search of the camp, Max is captured by the fungus, and Ben has to come to the rescue. Meanwhile, Gwen and the other children have to fight off an army of living mushrooms and other plants bent on using them as fertilizer.

Grandpa Max wants to find an ancient weapon, which happens to be unearthed in Texas before the Organization gets it. Using the ancient Mayan mask they locate the temple of the Mayan War God's sword. The Organization tails Grandpa Max and finally captures the Mask. While Ben as Fourarms battles the Guardian, Grandpa Max fights two of the organization and their leader for the sword. When Enoch finally obtains the sword it crumbles into dust. Laughing, Grandpa Max suggests that it's what happens when the "ultimate weapon" is 5,000 years old.

Gwen's powers return after she buys the magical Keystone at a convention in Las Vegas. But Hex and his niece Charmcaster want their hands on it. Charmcaster manages to trick Gwen by putting on an act about hating her uncle, only to swipe the Keystone while hugging Gwen. Charmcaster then gives Hex the Keystone. In the end it's revealed that Hex needed the Keystone to recreate the Charms of Bezel, and that Charmcaster was manipulating her uncle into doing it so that she can take the Charms power for herself. Ben stops the recreation process using Wildvine and defeats Charmcaster and Hex.

Our heroes ride a jet belonging to Grandpa Max's old Friend, Donovan Grand Smith, who owns an underwater resort. At the entrance, they receive a warm welcome from Donovan himself, though they also meet with his grandson, Edwin, who didn't seem to be excited about their guests. Later, when Edwin, Ben, and Gwen enter the Undersea Manta Ray, a giant submarine, they encounter strange aliens that threatened to destroy the whole resort. While the kids find a way to cooperate with each other to find the source that lures them in, Donovan himself learns a few lessons in how to bond better with his grandson.

Lately, Ben has been having strange dreams about Ghostfreak. During a tour of a school Gwen wishes to attend, Ben starts seeing Ghostfreak everywhere, and bad luck follows him around. When Frightwig, Acid Breath, and Thumbskull show up to steal some trophies, he inadvertently becomes Ghostfreak. After a vicious battle, during which Ben is clearly no longer in control, Ghostfreak escapes from the Omnitrix. Ghostfreak explains that when his DNA was sampled, a copy of his personality remained within the sample, and he's been trapped in the Omnitrix ever since. Now that he's free, he needs the power of the Omnitrix to become whole again, and he can only get that by possessing Ben.

When Ben tries to take apart the Omnitrix to see how it works, he ends up breaking off its face and causing weird combinations of his alien forms when he transforms. Additionally, the broken piece begins mutating the smaller creatures it comes into contact with. Meanwhile, Dr. Animo escapes from prison and, during a battle with Ben, finds the broken piece of the Omnitrix. Using it, he is able to complete his large-scale Transmodulator, giving him the power to mutate the entire planet in a single shot.

When Ben accidentally figures out the master code of the Omnitrix, he finds that he can become any alien just by thinking about it, and stay an alien indefinitely. However, trouble lurks as Vilgax and Kevin team up to destroy Ben and get the Omnitrix.

When Ben and Gwen forget about Grandpa Max's birthday, the two kids wind up bickering over who's to blame. But when a mysterious stranger appears out of nowhere and kidnaps Gwen, Ben follows her into a strange portal. When the dust settles, Ben suddenly realizes where he is: the future, in which humans and aliens live peacefully. Ben, however, is taken aback when he learns that Gwen's captor is actually her own future self, and an accomplished magician to boot. Future Gwen reveals that the current Ben is now a world-renowned hero with 10,000 different alien forms. But, upon meeting his own future, Ben realizes that the future Ben is all business and just can't relax, not even for his own family.

While visiting a mega-mall, Ben and Gwen watch a hypnotist perform. Gwen volunteers Ben as a test subject, and the host, Sublimino, successfully hypnotizes him. When asked to act like an alien, Ben naturally turns to the Omnitrix and almost changes in front of the audience. Even though he is stopped by Gwen, the trouble doesn't end there. Sublimino is able to use those he hypnotizes to commit crimes in their sleep, and the alien-equipped Ben proves to be the perfect accomplice. Using Ben, Sublimino is able to steal parts to make a much bigger hypnotisim device, this time hypnotizing everyone in the mall except Ben.

While Ben and family are visiting Salem, Massachusetts, Charmcaster attacks in an attempt to switch bodies with Ben. Gwen, however, interferes, leaving the two trapped in each other's bodies. While Ben and Max continue unawares, Gwen escapes from jail and returns, convincing Ben of the truth before Charmcaster tries again. However, Charmcaster manages to swap their bodies once more, restoring Charmcaster to her true body while swapping Gwen and Ben. The two are swapped back in the end, and Charmcaster is defeated by Cannonbolt.

Ben, Grandpa Max, and Gwen come upon a bizarre Christmas village run by an Christmas-obsessed man who thinks Grandpa Max is Santa Claus and proceeds to trap him. As Ben and Gwen explore, they learn about a strange curse on the village from one of its few unloyal elves.