Alien X

Alien X is a Celestialsapien from the planet Zvezda. He is an Omnitrix alien that appears in Ben 10: Alien Force.

Biography
Ben acknowledges Alien X as one of his most powerful aliens, however, he cannot afford the cost that comes with becoming the alien. Alien X is a being capable of warping reality at whim (unlike Anodites). He has a black body covered with tiny white stars, white hands and feet, green eyes, and three horns protruding from his head. He has three distinct personalities: Serena the voice of love and compassion; Bellicus the voice of rage and aggression; and Ben, the voice of reason. All three speak in unison when Alien X speaks. In order for Alien X to perform any action, including but not limited to simple movement and transforming back into Ben, two of the three personalities must agree to do so. As both Serena and Bellicus have been arguing for an eternity, and before Ben had no tiebreaker, getting them to focus on any present task is difficult at best, leaving the body of Alien X frozen in place while Ben attempts to convince them to act. Alien X first appears in X = Ben + 2, where Ben uses the form to stop a flood caused by a broken dam. After much fruitless argument, Ben eventually convinces them to transform him into one of his other nine aliens. He swears off using the form afterward, as it isn't worth the price the power comes at.

Abilities
He possesses vast reality warping powers, meaning he can make his thoughts become reality, alter matter, control living things, actions and thoughts, manipulate time; have the powers and appearance he wants, and (as confirmed by Bellicus in X = Ben + 2 when he states that Ben will never change back) stay in this form as long as he wants, in a few words he can do anything.

Weaknesses
In order for Alien X to perform any action, including but not limited to simple movement and transforming back into Ben, at least two of the three personalities (Serena, Belliscus and Ben) must agree to do so. This reveals to be a major weakness, as the personalities initially weren't even interested in dealing with present affairs and wanted to finish some past ones that weren't possible to deal with without Ben (with a comical scene were Bellicus reopens a discussion on whether or not to save dinosaurs from extinction).

Translations

 * Italian: Alienics/Possibly X is refered as nics.
 * Burmese: All-Knowing

Trivia

 * He has only been used once, in X = Ben + 2, making him the least used alien in theSerena_and_Bellicus.jpg Alien Force series.
 * Alien X is Ben's most powerful alien, but it is also his most risky to use.
 * Before he appeared the opening showed only a shadow of him, after he did it showed a normal image.
 * Alien X is also seen as a hologram while Albedo looks through the Ultimatrix in the episode The Final Battle: Part 1. He did not use this form to change himself because he already knew the risks of using this form and chose not to and also because Ben has arranged things so he can't (Dwayne McDuffie confirmed this)
 * The X in his name is probably used to signify him being the 10th alien by the Roman Numeral 10. It may also relate to its mysterious nature, as X is often used in Mathematics to represent an unknown number.
 * At the beginning of the video game Vilgax Attacks, Ben starts to turn into Alien X. But Paradox tells not to yet, but later in the game there is a cutscene where he sends Vilgax and Psyphon to the Null Void. In the DS version, after being defeated by Ben, Albedo turns into Alien X but is frozen and can not do anything. After the credits in the last level, we see a cutscene where Albedo is still frozen in Alien X.
 * Due to the fact that Alien X was on the spoiler poster, and seen on the prototype Ultimatrix alien designs, it is known that he will be in Ben 10: Ultimate Alien (he also appears unsilhouetted in the opening, indicating he might be a major alien in the new series). It is almost impossible that he will be evolved by Ben, due to the fact that he is already powerful enough but another possible idea might be that all 3 personalities may be combined, thus eliminating all arguments between them.
 * He is also becoming a "Nano" and a NPC in Cartoonnetwork's "Fusion Fall."
 * Bellicus's name is probably based on the word bellicose, meaning aggresive or eager to fight, while Serena's name is probably based off the word serene, meaning calm or peaceful, both references to their personalities.
 * He is seen as a hologram in Escape From Aggregor only it looks like he has a rock covering.
 * Alien X appears to be made up of space himself, hence the stars all over his body.