Ben 10 Omniverse: Ultimate Alien is a spin-off series of Ben 10 Omniverse, created by Omni11, where Ben regains the ability to evolve his forms, by turning the new omnitrix to an even better ultimatrix than the first one.
Ben, along with Rook and the rest of the team, battle against five of their worst enemies. At major disadvantage, Asmuth creates another source to evolve Ben's form, making it easier to defeat their enemies
1. Ben Tennyson - World's greatest hero, and wielder of the new and improved, ultimatrix. Along with his partner Rook, cousin Gwen, Grandpa Max, and best friend Kevin, he saves the world from it's greatest threats.
2. Rook Blonko - Ben's new by the book, partner and plumber in training. Helping Ben with every threat he faces.
5. Kevin Levin - Ben's best friend, with the power to absorb matter, helps Ben save the world when he and Gwen come and visit.
6. Azmuth - The creator of the omnitrix
1. Ultimate Battle: part 1 - Ben must save Asmuth after he is captured by Albedo, who has released four of Ben's greatest enemies. Asmuth is forced to create an ultimate power source for Albedo, when he threatens to kill Ben.
2. Ultimate Battle: part 2 - Ben struggles to free Asmuth when five of his greatest enemies get upgraded. Gwen and Kevin join to help with what will be Ben's greatest battle yet.
3. Battle Beyond - Ben meets a new friend, when he gets stuck in a dimension outside his own. Now They must work together to find a way out, while trying to escape aliens, who can travel between the dimensions.
4. Schooled Out - After Ben gets detention, the Forever Knights put the school under lockdown. While Rook, Max, and the plumbers try to get in and save the students, Ben must save his classmates and escape.
5. Nightmare of a Future - When Hex and Adwaita merge bodies, they gain ultimate power over magic. They scatter the team across different dimensions. First, Ben is sent to a future where the faction rules Earth, where he went missing, Gwen and Rook lead the existence, and Max and Kevin were lost fighting.
6. OmniEarth - When Hex and Adwaita merge bodies, they gain ultimate power over magic. They scatter the team across different dimensions. Second, Kevin is sent to a dimension where Ben doesn't turn into aliens, but draws them out of the omnitrix to control them.
7. Long Time no See - When Hex and Adwaita merge bodies, they gain ultimate power over magic. They scatter the team across different dimensions. Third, Max is sent to dimension 23, where Ben 23 is startled to see the grandfather he lost years ago.
8. Now Your an Alien, Now Your Not - When Hex and Adwaita merge bodies, they gain ultimate power over magic. They scatter the team across different dimensions. Fourth, Gwen is sent to a world, where Ben never got the omnitrix, but Vilgax got it instead. Now, Gwen must stop Vilgax and help Ben receive the omnitrix, so he can be the hero, the Earth needs.
9. Galvan Prime to Rook - When Hex and Adwaita merge bodies, they gain ultimate power over magic. They scatter the team across different dimensions. Finally, Rook is sent to a dimension where there's no Earth, but have Galvan counterparts. Rook must now help Ben's and the team's counterparts fight Vilgax.
10. Return to Earth, I Think - After returning back to Earth after the events of Across Dimensions, the team finally returns to "normal" Earth. When things start going crazy, the team figures out it's all an illusion, by Dr. Animo.
11. Ultimate Ultraman - When the ultimatrix malfunctions, Azmuth has to fix it. Meanwhile, Blukic and Driba make ben an exo-suit, that gives him powers. Ben then becomes his old superhero persona, he had imagined himself as when he was 10, Ultraman.
12. Team-Up - Ben is still using the exo-suit as Ultraman, as Azmuth is close to being finished fixing the Ultimatrix. When Dr. Animo transforms people of Bellwood into insects, only Ben and Gwen are still normal. Now, Ultraman and Lucky Girl can stop Animo.