Episode 1
Ben is tasked with cleaning the Rust Bucket, but when he is tricked into letting the villainous and vile Fly Guys steal it, he must chase them down before they create an unstoppable maggot monster.
Episode 2
Ben, Gwen, and Max's trip to Niagara Falls is cut short by the horrid Hydromanders - creatures menacing them and their fellow tourists.
Episode 3
Ben and Gwen's camping trip is interrupted by the emotionless Weatherheads - Gust-o, Hail-o, & Shock-o - but a malfunctioning Omnitrix firing out a mishmash of aliens may not be the forecast for success.
Episode 4
Episode 5
Ben must overcome his fear of squids when the Steampunk super villain Steam Smythe attacks a construction site of Grandpa Max's favorite pier.
Episode 6
While trying to film his own indie film, Ben accidentally allows the Bug Gang to go free and when he takes the fight to their hidden lair, Ben has to take on their narcissistic leader - the Ant Queen.
Episode 7
Ben and Gwen are turned into babies by a weird nanny who wants to turn the world into a day care.
Episode 8
While chilling at a monastery with a no-noise policy, Ben can't keep quiet and accidentally awakens a dangerous Dragon hidden in a secret chamber below the hallowed halls - a job that might be too much for even Diamondhead.
Episode 9
When a wizard cos player gets his hands on a real magic wand at Comic Con, Ben enlists the help of Gwen (as Lucky Girl) to help stop Hex from retrieving it by tricking the wicked warlock into thinking she is a possessor of powerful magic herself.
Episode 10
Ben stumbles into Dr. Animo's secret lab - now ruled by his superior mutants, the Alphas - and must help the lesser animals escape while stuck as Stinkfly.
Episode 11
While tailgating at a State U. homecoming football game, Ben teams up with Grandpa Max's old college buddies to keep the crazy clown Zombozo from robbing the stadium blind at halftime.
Episode 12
Gwen, Ben and Max encounter a family who are kind of their mirror selves.
Episode 13
The Tennysons visit Fort Know, but it does not last long till Ben has to fight a monster.
Episode 14
In the heart of Silicon Valley, Ben has to stop Victorian villain, Steam Smythe, from getting an incredible power source sealed in a Tesla time capsule.
Episode 15
Dr. Animo returns with his newest invention, the 'Animerger'.
Episode 16
No one believes Ben when he insists that one of the other patrons, waiting in line at the World of Wet Water Park, is the nefarious Frightwig, disguised as a common girl called Frida.
Episode 17
A man attempting to be a hero ends up misusing his abilities, and Ben has to stop him.
Episode 18
Ben and Gwen decide to race against LaGrange when he crashes a race.
Episode 19
The group visit the Buddy's Vision Of Tomorrow exhibit, where Steam Smythe hopes to take a secret weapon to rule the world.
Episode 20
Hex returns for the large spellbook Grimoire of Archamada which contains a high-level spell that will make him more powerful than ever.
Episode 21
While golfing, Ben must face a biker gang of mutated groundhogs.
Episode 22
When Ben puts out a fire as Wildvine, a trio of alien chiefs decide to eat him for lunch.
Episode 23
Ben finds a rare map in the historical village Oldeville. Billy Billions wants that map so he challenges Ben with his high-tech drones.
Episode 24
When Ben interferes with malicious magician Hex's quest for the earth-moving Titan Gloves at a swap meet, he switches bodies with Gwen forcing him to walk a mile in her shoes and vice-versa!
Episode 25
Ben and Gwen want to stay awake in Adrenaland, a theme park that is 24/7 open. Thinking that with his alien abilities he can stay awake, things get worse.
Episode 26
Ben, Gwen and Max stop by the graveyard set of a movie, The Unalivers. Before long, Ben discovers its leading role, Michael Morningstar, is a energy-absorbing vampire.
Episode 27
When a new enemy causes Gwen and Max to become super-lazy, it's up to Ben to snap them out of it and finally get serious in order to put things back to normal.
Episode 28
Gwen and Ben are excited to attend an Earth Day EDM concert in Portland until the show is hijacked by the sound/music/audio-manipulating villain, Lord Decibel.
Episode 29
Ben hangs out with his weird former-babysitter named Penny when they arrive at a pig festival while Maurice and Sydney create a helium weapon for their next big heist.
Episode 30
Zombozo returns with the Circus Freaks, (Frightwig, and 2 new members, Thumbskull and Acid Breath) with a new plan to turn everyone into clowns like him.
Episode 31
During a hunt for the fabled 'Forgeti', (who Gwen is fascinated and obsessed with), Ben and Gwen face Dr. Animo once again when he kidnaps Max for his latest experiment.
Episode 32
When Maurice and Sydney accidentally split Max into 100 dumb clones of himself, Ben must find a way to switch him back without getting divided as well, while Gwen is forced to babysit the Maxes.
Episode 33
Ben wants to earn some money by mowing Bob's lawn. He rebuilds the lawnmower into a super fast-mowing machine, but in doing so he angers the little stubborn gnome neighbors.
Episode 34
Ben's favorite cartoon character, Xingo, comes out of TV into the real world when Upgrade tampers with the TV satellite.
Episode 35
Ben needs to pretend that he is not scared when staying in a haunted hotel.
Episode 36
Touring Yellowstone National Park, Ben uncovers a plot by Lagrange who wants to digout an old treasure from below the national park.
Episode 37
Ben's trip to Portland with his family is interrupted by the arrival of a brand new, eleventh alien, Gax, as he fights another one of Dr. Animo's monsters. But when the Omnitrix starts behaving strangely, Ben begins to transform from one alien to another without being able to stop.
Episode 38
As the Omnitrix is still uncontrollable, Ben asks a mysterious friend of Max to repair it. But when three bounty hunters, Sixsix, Kraab, and Tetrax land to recover the watch, Ben has to try and fight them despite his current predicament.
Episode 39
Ben heads far into the forest to prevent his unpredictable transformations from causing damage. Meanwhile, Vilgax, who seems to be the same species as Gax, lands nearby. The latter helps Ben discover his powers, but he quickly realizes that this new friend is in fact an opponent.
Episode 40
After his meeting with Vilgax, Ben continues to transform rapidly without stopping or be able to revert to human form. While Vilgax tries to take the energy of a volcano to recharge his ship and return home, Ben gets the idea to "update" the Omnitrix and thus save the planet from his enemy. But what did he do exactly?
