Ben discovers that the Forever Knights are trading weapons with the DNAliens, while at the same time, Grandpa Max has mysteriously gone missing. He decides to return the Omnitrix on his wrist and go hero once again.

Ben, Gwen, and Kevin follow a lead that takes them to a secret base in the desert. There they hope to find Grandpa Max but instead find a Highbreed spaceship with a giant cannon.

Kevin shatters Ben and Gwen's trust when he steals the Rust Bucket to sell for alien technology on the black market.

Gwen's older brother, Ken, is suddenly missing. As they look, they encounter a surprise leading to a shocking secret from the DNAliens.

When Ben and Gwen learn that their grandmother Verdona is an alien being, Verdona insists that Gwen should come along with her to her home planet and improve her abilities. With this, Gwen is faced with a difficult decision between a human and alien life.

A time experiment in the 1950s sends a bizarre monster to Ben's time. Now Ben, Gwen, and Kevin must team up with Paradox, a time traveling hero, to face off against the unstoppable creature.

An alien emperor plans to destroy the planet Earth for kidnapping his daughter. In order to save the planet, Ben must uncover the secrets of Alien X.

During a battle Ben and an alien commander are teleported to a distant world. They must put their differences aside if they're going to have any chance of finding a way to return to Earth.

An alien impersonates Ben with hopes of using his Omnitrix to annihilate him.

Cooper is kidnapped by the DNAliens, who want him to build a mystery arch.

After Gwen receives an S.O.S. from Helen, Ben must go into the Null Void to save her and Manny. Once there, he must find The Wrench in order to stop D'Void, who happens to be Ben's old enemy Dr. Animo

Ben cares for a baby monster and helps locate its parents before the DNAliens find it.

Ben goes to the HighBreeds' world in an attempt to stop their attack on Earth.

Vilgax, after conquering 10 planets, comes to Earth to destroy Ben.

Ben, Gwen and Kevin race to collect the Omnitrix's missing forms and make it to the battle with Vilgax on time. Meanwhile, Kevin discovers that his new transformation has some benefits.

A series of earthquakes awakens a HighBreed officer who has been hibernating deep under the earth’s surface. He believes the HighBreed have lost the war and activates a fail safe device that is programmed to destroy. Ben must now work together with Gwen and Kevin not only to save Grandpa Max, but also the world from this "giant" problem.

Kevin makes a temporary truce with Darkstar to retrieve an artifact that will return them into their former selves.

The Omnitrix transports Ben, Gwen, and Kevin to a planet called Primus, which turns out to have been created by Azmuth. They must stop Vilgax from stopping the Omnitrix at its source.

The Plumber's Helpers are called upon by Grandpa Max to rescue him from an abandoned space station where he's being attacked by Ben! The team must now find a way to work together as they try to save Max, stop Ben, and keep the space station from crashing to Earth.

Albedo has stolen the Ultimatrix from Azmuth and has used it to kidnap Gwen and Kevin. Ben goes to face Albedo and rescue his friends when he quickly discovers that Albedo has been working in conjunction with Vilgax. Ben is defeated by the pair and gives up the Omnitrix to save himself and his friends.

Powerless, Ben goes aboard Vilgax's ship and faces off with Vilgax to stop his invasion of Earth in their final battle. Albedo gives Ben the Ultimatrix and Ben gets his old aliens and their evolved forms.