"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.