Alien X is the Alpha-Omegatrix's DNA sample of a Celestialsapien from the Forge of Creation and Zvezda.
Alien X is a humanoid alien that has pink hands. He is all red excluding his hands. He has tiny pink stars distributed on his body. His red are green with no pupils. On his head are 3 horns like Ultimate Way Big. Unlike most of Richard's aliens, Alien X has five fingers, and no toes.
Alien X wears the Alpha-Omegatrix symbol on his chest.
In Alpha-Omegaverse, Alien X retains his original appearance, but his chin is now bigger like Diamondhead. He is more muscular. The Simplicitrix symbol is on his chest.
Alien X has shown to be omnipotent, able to warp reality and time/space itself, becoming nearly invincible.
Alien X's reality warping is so powerful, that his mere thoughts can become real.
Because Alien X is Richard's most powerful alien or Richard thinks, although Alien X is not the most powerful alien in the Alpha-Omegatrix, but does carry the most risk.
In order for Alien X to perform any action, including but not limited to, simple movement and transforming back, at least two of the three personalities must agree to do so. This reveals to be a major weakness, as Serena and Bellicus weren't interested in dealing with present affairs and wanted to finish past ones that weren't possible to deal with without Richard (with a comical scene in Ben 10: Alien Force where Bellicus reopens a discussion on whether or not to save the dinosaurs from extinction).
There is an alternate timeline where Drahcir transformed into Negative Alien X and was stuck motionless for nearly a year, although Drahcir is confirmed to use him again in the main timeline.
Alien X is vulnerable to having his powers absorbed.
- Richard first uses Alien X in In Alien X We Trust?.
- Darama gains the Alpha-Omegatrix and uses Alien X in Rath of Darama.
- Darama regains the Alpha-Omegatrix and uses Alien X again in All Out War Part 2. The Alpha-Omegatrix is destroyed while in this form, causing Darama to revert back and be severely injured.
- Alien X reappears in Maklar's Surprise to defeat Darama and revive Cilocub.
- Alien X is used in Isn't There Someone Else You Can Annoy?.
- In All The Time In The World, Paradoox stops time and transforms Richard into Alien X in his dream so he can be warned of the danger coming.
- Maklar's Surprise (first reappearance)
- Isn't There Someone Else You Can Annoy?
- All The Time In The World (dream)
- Before his debut, Richard thought that Alien X was either a joke or a myth, similar to Rook's thoughts on Ben's Alien X, also Maklar's thoughts on him until Maklar's Surprise.
- In Intergalactic Encounters, he is replaced by Alien R, Cursed Phantom, and Un-Named.