Brainstorm

"Their advantage: superior numbers. My advantage: superior intelligence." - Brainstorm in The Vengers

Brainstorm in Ben 10: Omniverse

Brainstorm is a Cerebrocrustacean from the planet Encephalonus IV. Ben first transformed into him by accident due to a signal interference in Pier Pressure where he fought and defeated Ship. Brainstorm is notable for being the only alien Ben named on screen, instead of instantly knowing the name of the form. 

Lodestar

Lodestar in Ben 10: Omniverse

Lodestar is Ben's Biosovortian alien form that first appeared in the Ben 10: Alien Force episode Simple as an accidental transformation where he takes away guns from the red troopers. He was unlocked in the end of War of the Worlds: Part 2 and was used off screen. Lodestar returned in the Ben 10: Ultimate Alien episode Duped where he defeated Urian. Lodestar made his Ben 10: Omniverse debut in the first episode The More Things Change: Part 1. He is voiced by Dee Bradley Baker.

Spidermonkey

"Why Grandma, What big trouble you have!" - Spidermonkey in What Are Little Girls Made Of? 

Spidermonkey in Ben 10: Omniverse

Spidermonkey is an Arachnichimp from the planet Aranhaschimmia. He is one of the original ten in Ben 10: Alien Force who makes his debut in What Are Little Girls Made Off? where he battled Verdona. He reappeared in the Ben 10: Ultimate Alien episode Fame where he battled Bivalvan before assuming his Ultimate form. Spidermonkey returned in the Ben 10: Omniverse episode The More Things Change: Part 1 where he battled Crabdozer, mostly trying to dodge and run away from the predator. Spidermonkey is voiced by Dee Bradley Baker.

Chromastone

"Holy moly, it's Chromastone!" - Chromastone in A New Dawn

 

 Chromastone is a Crystalsapien from the planet Petropia. He first appeared in the Ben 10: Alien Force episode All That Glitters where fought against some energy-drained high school girls. Chromastone was destroyed in Vengeance of Vilgax: Part 2 and reformed into Diamondhead, however he was re-unlocked in the Ben 10: Ultimate Alien episode Fame where he was defeated by Bivalvan. 

Chromastone briefly appeared in the Ben 10: Omniverse episode Trouble Helix where he was a test subject for Blukic and Driba's new weapon. He didn't appear again until the final episode of Ben 10: Omniverse, A New Dawn, where he tried to retrieve the Anihilaarg. He later briefly appeared while Ben was cycling through almost all of his aliens. Chromastone was voiced by Dee Bradley Baker in Alien Force and Ultimate Alien. Eric Bauza voices Chromastone in Omnivese.

Jetray

"Check this out! I can shoot lasers from my eyes and my tail!" - Jetray in Video Games

Jetray in Ben 10: Ultimate Alien

Jetray is one of Ben's original ten aliens in Ben 10: Alein Force. He's an Aerophibian from the planet Aerophibia. He first appeared in the Alien Force episode Everybody Talks About the Weather where he chased Alan. Jetray returned in the Ben 10: Ultimate Alien episode Fame where he saved a pilot. Jetray is voiced by Dee Bradley Baker.

Alien X

"Surprise!" - Alien X in Universe vs. Tennyson

 Alien X is a Celestialsapien from the Forge of Creation. He first appeared in X = Ben + 2 where he stopped a dam from flooding, Ben then spends most of the episode negotiating with Bellicus and Serena. He reappeared in The Forge of Creation trying to convince Bellicus and Serena to locate the Forge of Creation before Ultimate Aggregor does, before Professor Paradox intervenes and reverts him back to normal. Alien X was then used in the Omniverse episode So Long, and Thanks for All the Smoothies where he created a near-identical copy of the universe, as the old one was destroyed by the Anihilaarg. Alien X is voiced by Yuri Lowenthal.

Appearance

 Alien X is a humanoid alien with stars covering his black cosmic body with white highlights. He has two green eyes and three horns on top of his head. In Omniverse, Alien X is now more muscular, has a bigger chin and his horns are smaller. The Omnitrix/Ultimatrix is located on his chest.