List of ''Ben 10: Ultimate Alien'' episodes

Ben's secret identity is revealed to the entire world, and he is now a superhero loved everywhere by kids and teenagers, but distrusted by many adults. Kevin and Gwen find out who revealed Ben's secret and where he lives, and the three go to "pay him a visit". The informant turns out to be a young boy named Jimmy Jones, who has followed Ben's exploits ever since he was ten-years old. With Jimmy's help, Ben and company discover a series of alien attacks in Florida. The unknown alien steals a nuclear device from a prototype interstellar rocket. The group follow the alien to its hideout and defeat it, learning that the alien is from another galaxy, having been kidnapped by a being named Aggregor.

Julie is playing her first big game, while the Forever Knights are trying to break into a museum. Ben also wants to go see the opening of a new Sumo Slammers movie. To deal with his dilemma, he transforms into Echo Echo and then changes back to human, creating three copies of himself with differing personalities. The arrogant Ben gets sent off to watch Julie's game, the kind Ben goes to help Kevin with the Forever Knights, and the rational Ben goes to watch the movie.

After Ben's secret identity is revealed, a bunch of his old enemies start attacking his family as a method of revenge.

Ben is approached by a video game producer in order to make a Ben 10 video game. Unfortunately, this producer is actually working for Will Harangue, who intends to create a robot to destroy Ben. The producer has all of Ben's aliens scanned, in order to have the robot learn their moves. The robot begins to attack, with a climactic showdown happening on the National Wall in Washington, D.C.

Ben defeats an alien who was rampaging through Bellwood. The alien, named Galapagus, chronicles how he was kidnapped from his home world by Aggregor. He explains how he met five other aliens, and they escaped him to end up crash landing on Earth. Ben mentions how they already found Bivalvan, and promises to make sure all the aliens are returned home.

A strange alien is offering big money (over $1 million) to someone who can open a safe (which is really a containment suit). That alien is revealed to be P'andor, who wants to be free of his suit. Eventually, Kevin accidentally releases P'andor in his radioactive form, whom Ben, Gwen, and Kevin have to stop.

If the castles Argit goes to refuse to let him rule their castles, he will use his new friend Andreas to destroy the castle. Andreas is also one of Aggregor's victims. Jetray then scans Andreas' DNA and gains a new form and transforms back into Ben. Argit gives Kevin money as payment for the money he owes him. Kevin then says that he loves money more than anything else in the world and Gwen gets mad at him for the remainder of the episode. Argit tells Andreas that Ben and his team are friends, but then a Forever Knight intelligence officer named Sir Dagonet comes in and turns Argit's Forever Knight garrison against Ben and his friends.

As Ben laments that things can't get worse, Aggregor shows up to recapture Ra'ad. The gang try to fight Aggregor, but he proves to be too strong for them. The Ultimatrix finally lets Ben transform, but unfortunately, all that he can transform into is an Amperi. With no choice, Ben transforms into AmpFibian and fights Aggregor.

He then kidnaps Julie, who was shown taking her anger over Jennifer out on the tennis courts. Nemesis then intercepts Jennifer's helicopter. When Ben calls Julie, Nemesis answers the call and tells Ben to "come and get me" if he wants to see her again.

Aggregor then begins to absorb energy and Kevin tries to reason with him, explaining that regularly absorbing energy caused him to go insane when he was a kid but Aggregor doesn't listen, claiming that it is a lie told by powerful Osmosians to control the weak Osmosians. Before Kevin can reason with him any further, Aggregor shoots Kevin with his spear. He then powers himself up and breaks the fabric of time.

Continued from the previous episode, Aggregor has absorbed the powers of Bivalvan, Galapagus, P'andor, Andreas, and Ra'ad, transforming him into Ultimate Aggregor. Ben transforms into Humungousaur and attacks Aggregor in a fight of rage and anger, seemingly pummeling him unconscious.

The Forever Knights discuss their plan for the weapon and Ben and the team come in to fight with Cash, J.T., and Oliver filming the scene. Kevin gets angry with them not helping and Psyphon comes in to destroy Cash and J.T., believing them to be the masterminds behind Ben Tennyson.

Azmuth contacts Ben on the Ultimatrix and is not happy with him for failing to stop Aggregor from claiming three of the four pieces to the Map of Infinity. When Ben tells Azmuth that scolding him is not going to help, Azmuth agrees and then teleports Ben, Gwen, and Kevin to the Rust Bucket 3 in another galaxy, in which they find the Perplexahedron, a giant cube-like artificial planet. Moments later, they spot Aggregor approaching the planet.

With Ultimate Aggregor having all four pieces of the Map of Infinity, he'll be on his way to the Forge of Creation (Alien X's home planet). Professor Paradox helps Ben, Gwen and Kevin get to they need to go, but after Paradox left, Ben and the others ran into Ben's younger self. The four of them arrive at Alien X's home planet, where they battle Ultimate Aggregor and after Kevin gone insane in absorbing Ben's powers he defeated and absorbed Ultimate Aggregor. 10-year-old Ben goes back to where he belong from Professor Paradox.

Omnitrix alien debuts: Heatblast (10-years-old), Wildmutt (10-years-old), Four Arms (10-years-old), Stinkfly (10-years-old)

Zarcovia's soldiers has found the frozen body of Dr. Viktor. Prince Gyula and King Xarion want to see this weapon. Gyula wants to control Dr. Viktor to use him against rebels in their civil war, but Xarion tells him not to. King Xarion asks for help from Ben, Gwen, and Kevin and explains what Gyula is trying to accomplish. When they find Dr. Viktor's corpse, they are found by Gyula's soldiers. While fighting them, Dr. Viktor's ice block begins to melt and he breaks free; Gyula reveals that Dr. Viktor is under his control.

Ben, Gwen, and Kevin are summoned to Plumbers Academy to go under training. They create a good friendship with an alien named Tack and Ben dislikes the drill instructor, Magister Hulca, that is being targeted for revenge by a menacing Tetramand.

The secrets of Area 51 are revealed to Ben Tennyson by Colonel Rozum after Old George infiltrates and destroys it, setting free the 775th prisoner.

The ultimate aliens inside Ben's Ultimatrix demand their freedom and end up sucking Ben into the Ultimatrix. While Gwen assumes her innermost Anodite form as her astral projection to enter the Ultimatrix to help Ben, Kevin travels to planet Galvan Prime to convince Azmuth to help.

Vilgax and the Flame Keepers' Circle fight against George and the Forever Knights along with Ben. Vilgax gets Diagon's heart and ends up being sucked into Diagon's own parallel dimension.

Techadon Weapon Master Number 13 arrives on Earth and demands to have the Ultimatrix. A malfunction grants Gwen and Kevin the forms and unique abilities of some of Ben's aliens.

Dr. Animo returns with a plot to transform eggs into pterodactyls.

Ben fails to defeat the extradimensional Diagon, who proceeds to destroy Sir George by electrocuting him with dark lightning. Vilgax returns, capturing Diagon by Psyphon's power-absorbing machine. Psyphon proceeds to transfer Diagon's power to Vilgax, making the galactic conqueror into a nearly-unstoppable force. Ben wields George's sword, Ascalon, and uses it to drain Diagon's power from Vilgax. Reverted to his original form, Vilgax tries to corrupt Ben, asking what he plans to do with the combined power of Ascalon, Diagon, and the Ultimatrix but Gwen and Kevin both encourage Ben to resist Vilgax's temptation. Ben uses his infinite godly abilities to transform the Esoterica back into humans. Azmuth appears before them and asks Ben to return Ascalon and the Ultimatrix to him. He gives Ben a new version of the Omnitrix.

Ben teams up with an alternate superhero, Rex Salazar, to save the Earth from a deadly Alpha Nanite that entered New York through a swirling vortex, the same way Ben arrived in the city.