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.

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

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.

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.

Ben, Gwen and Kevin gather their allies to counter the threat of the incoming Highbreed fleet. Azmuth reveals a secret about the Omnitrix.

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

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.

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.

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

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, 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.

Zaw-Veenull asks Ben to deliver Prince Tiffin to Jarret in order to keep peace between the two species. Shortly, after their trip in space, the Omnitrix malfunctions and turns Ben into an Appoplexian named Rath who wants to fight anything that breathes.

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.

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.

A new villain comes into town, his name is Darkstar, he commits some crimes and gets the team's attention fast

Kevin asks Gwen to the school dance; Ben fears he's losing control of the Omnitrix.

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

Ben and the gang rescue a runaway prisoner of the DNAliens.

While Ben has a date with Julie, it is soon ruined when an alien named Ship makes trouble at the local fair.

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.

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.

Despite being warned by Paradox, Gwen travels back in time to prevent the accident that turned Kevin into a monster from ever happening. Gwen returns to the present only to find that her time traveling caused a series of events that led to Hex ruling the world.

While sick, Ben is visited by old friend Tetrax, who demands that Ben hand over Chromastone.

Kevin returns home to find his house ransacked, so he enlists Ben and Gwen's help to find out who did it and why. They soon cross paths with Ragnarok, a deadly criminal who recently broke free from the Null Void and is in search of a special key. Kevin is intent on stopping Ragnarok from obtaining the special key, especially after he learns the truth about Ragnarok and his father.