Ben 10

Average kid, ten year old Ben Tennyson, his Grandpa Max and his Cousin Gwen's summer of adventure takes an odd turn when Ben discovers a watch-like object (the Omnitrix Prototype) that has been jettisoned from alien spacecraft high above the earth. When the prototype attaches itself to Ben's wrist, he discovers that it allows him to become any one of ten aliens. Ben's first test as a hero comes early as Vilgax sends mechadroids to procure the prototype.

While stopped at a lakefront campsite, Ben has a chance encounter with a Loch Ness-type sea monster called a Krakken. Eventually, Ben discovers the true threat--the evil poacher Jonas and his high-tech deep water thieves--who are arousing the Krakken by trying to steal its eggs.

Grandpa, Gwen and Ben visit a spinster relative only to find that her retirement community has been overtaken by a shapeshifting aliens called Limax. The Limax are systematically gathering the elder population for transport back to their home planet to use as a food source. Ben must use his alien heroes to defeat the Limax and rescue not only his matronly aunt but also Grandpa Max.

Ben finds himself hunted down by three alien bounty hunters--the crustacean-like Kraab, the mechanical assassin Sixsix and the mysterious hoverboard--hired by Vilgax to procure the prototype watch. The experienced and powerful mercenaries provide Ben's alien heroes with their first true challenges. Fortunately, Hoverboard is a double agent working on the side of good to make sure the Omnitrix doesn't wind up in the wrong hands. Unfortunately, he is not too pleased that Ben treats the most powerful weapon in the galaxy as a toy.

When Ben can't resist messing with the world's largest rubber-band ball at a cheesy roadside tourist-trap town, he accidentally releases Megawhatts, mischievous and destructive creatures made of electrical energy with the power to warp reality to their own sinister prankish delight, that were living inside. Ben must then use his alien hero personas and his own practical joke-loving ideas to recapture the Megawhatts before they can threaten a major population center.

After a blow-out argument with Max, Ben rebels by going out on his own in the Big Apple. He soon makes friends with Kevin, a mutant with the power of to absorb any form of energy to make himself even more powerful. At first, Ben is drawn into the allure of Kevin's nonconformist lifestyle, but he is soon forced to realize a cold fact: Kevin was only keeping him around until he could exploit and leech off the powers of the prototype--becoming Kevinized versions of the ten heroes, eventually absorbing all 10 heroes and becoming a mix of each alien--Kevin 11.

As Fourarms, Ben is working to thwart an armored truck robbery by a tough and heavily armed female gang leader named Joey, when he is attacked by a new set of Vilgax's Mechadroids. Fourarms defeats the robots, but Grandpa Max is injured in the melee. While Ben and Gwen look after Max in the hospital, Joey merges with the left over pieces of the Vilgax Drones and becomes Rojo, a cybernetic combination of the two. Vilgax "persuades" Joey to retrieve the prototype for him. Eventually, Ben is able to defeat the new-and-improved Joey, but not before she delivers a disturbing message from Vilgax.

Ben's fear of clowns emerges at an unfortunate time when our heroes stumble upon a wicked circus with a "psychic vampire" clown named Zomobozo as its ringmaster, who leads the venom-spewing Acid Breath, the Medusa-like Frightwig and the bizarre strongman Thumbs. When Gwen becomes caught in Zombozo's evil clutches, Ben must overcome his fears to save his cousin.

Ben battles Hexlord, an evil sorcerer whose power emanates from several mystic charms--one of which falls into Gwen's possession after the battle. She discovers the charm gives her incredible luck, and she quickly learns to focus it, deciding to become her own superhero, Lucky Girl. Soon the magician escapes from jail, tracks down his missing charm to Gwen and a big set piece confrontation ensues. In the end, Gwen must choose between her newfound power and defeating the evil sorcerer.

When Ben is prevented from riding an attraction at a water park because he isn't tall enough, he decides to go alien to get even with the ride's attendant. Unfortunately the unpredictability of the prototype watch causes him to become stuck as Grey Matter instead. To make the situation worse, Grey Matter is then kidnapped by a sci-fi geek named Howell, who intends to "unveil" his new discovery to a group of mysterious masked Illuminata types at a dark and strange mansion.

When Ben's actions cause him to catch a summer cold, the normal symptoms (watery eyes, stuffed up nose, cough, etc.) take on strange physical changes in his alien personas. To make matters even more difficult, Ben must stop a disgusting creature made from a colony of cockroaches while having to deal with these frequently funny, unusual and often debilitating side effects on his heroes.

Healed and enhanced from his injuries, Vilgax decides to procure the prototype himself rather than relying upon subordinates, mercenaries, etc. He arrives on Earth in his massive spaceship and begins trying to flush out the holder of the prototype in his mega-destructive War Wheel vehicle. Meanwhile, Max's mysterious past begins to come to light, including a personal history with Vilgax--culminating in the final showdown between Vilgax and the combined Tennyson family.