Alien X (Ken 10)

Alien X is the Omnitrix's DNA sample of a Celestialsapien from the Forge of Creation.

Appearance
Alien X is a humanoid alien whose entire body is solid black, excluding his hands, which are white. He has tiny white star-like spots all over his body, giving him the appearance of a starry night sky. His eyes are green and lack pupils, and his forehead bears three horn-like protrusions.

In Omniverse, Alien X is largely the same as before, but with minor changes. His chin is now bigger, his body is more muscular, his horns are smaller, and the stars on his body are brighter than before.

Alien X wears the original Omnitrix/Ultimatrix/Omnitrix symbol on his chest.

Personality
Alien X has three personalities: Serena, the "voice of love and compassion", Bellicus, the "voice of rage and aggression", and Ben, the "voice of reason". All three of these voices combine to form Alien X's speech. Otherwise, Alien X is silent. The only things he will say are what he will be doing - what Ben, Bellicus, and Serena have agreed to do.

As Serena and Bellicus have been arguing for eternity and before they had no tiebreaker, getting them to focus on any present task is difficult at best. This leaves Alien X's body trapped in place, floating about a foot above the ground until an agreement is made.

Powers and Abilities
Alien X is omnipotent, being able to warp reality, time, and space with ease and at any level he wishes. Even his thoughts can become real. In short, Alien X can do anything.

Alien X can create and recreate an entire universe at will.

Alien X possesses superhuman strength and is skilled at hand-to-hand combat.

Alien X is nearly invulnerable, as he was completely unharmed when the Annihilargh destroyed the universe around him.

Alien X can create time waves to reverse events in a specific area and black holes to suck in other beings such as another Celestialsapien.

Alien X can self-duplicate and fly at high speeds.

Due to the nature of his species' creation, Alien X can survive in the vacuum of space.

Alien X possesses telekinesis and is capable of deflecting energy attacks, such as those generated by a Prypiatosian-B.

Alien X possesses X-ray vision, meaning he can see through objects such as a mountain.

Alien X can survive a timeline destruction.

Alien X can regenerate his limbs should they be severed, as demonstrated by the Galactic Gladiator.

Alien X has the ability to shapeshift, teleport and grow to a gigantic size; these feats were also demonstrated by the Galactic Gladiator.

Weaknesses
In order for Alien X to perform any action, including simple movement and transforming back, all three of his personalities must agree to do so. This has proven to be a major weakness, as Serena and Bellicus were not interested in dealing with present affairs and wanted to finish past ones that were not possible to deal with without Ben. In Omniverse, Ben still needs to consult Bellicus and Serena to get control, he is just better at it now.

Alien X is vulnerable to having his omnipotent powers absorbed by Osmosians and entities with similar powers such as Darkstar.

Alien X's actions onto reality can be neutralized and reversed by the intervention of other Celestialsapiens.

Alien X can be devoured by a Gourmand, who would either digest him or spit him back out.

Alien X can be affected by a Nemuina's sleeping dust.

Alien X's personalities can be scared by Toepick's species.

Alien X's life force can be drained by a Vladat. He also cannot survive on Anur Vladias.

Alien X's powers may either be limited to the basic cosmic laws of other universes or may not work depending on the universe.

Alien X cannot manipulate mana directly because he would first have to alter the universe to change the nature of mana.

Alien X's cosmic powers do not work well against magic.

Trivia

 * Ben, Azmuth, and Professor Paradox all acknowledge that Alien X is the most powerful being in the Omnitrix.
 * However, Ben has conceded that transforming into Alien X is not worth the cost, as the risk is simply too great for him to use the transformation. Simply put, Alien X is too much of a pain for Ben to use unless there is no other option.
 * Alien X's starred body is not simply "aesthetic". Like all Celestialsapiens, Alien X contains his own "debate dimension", which exists inside his head. But rather than being a real place, it is a visual interpretation of what is happening mentally.
 * This explains how Paradox was able to travel inside Alien X and speak to Ben whilst he was arguing with Serena and Bellicus before reversing the transformation.
 * Much like his birthplace, Alien X exists outside the universe (i.e. time and space). Beings existing outside time and space are simultaneously everywhere and nowhere at the same time.
 * This also implies that since Ben Prime and Ben 10,000 share the same Celestialsapien DNA in their Omnitrices, the Alien X transformation used by them is the same Alien X, not just genetically, but literally.
 * Sometime between the events of The Final Battle: Part 2 and The Forge of Creation, Ben had had the Ultimatrix modified to lock the Alien X transformation, to both prevent himself from accidentally transforming into him and as a safety measure to keep someone like Albedo from using it. The only way to access Alien X was to use a pair of keys in Gwen and Kevin's possession. This is not the case for the new Omnitrix, in which Alien X is accessible without any keys, as the threat of Albedo turning into Alien X has been neutralized.
 * In Universe vs. Tennyson, Ben offers to let the two personalities argue between themselves for eternity if they give him full control over Alien X. Serena agrees, followed by an initially reluctant Bellicus, giving Ben full control over Alien X. This is seen again in Weapon XI: Part 1.
 * Albedo's Bellicus and Serena would appear red.
 * In A Jolt from the Past, Rook speaks of Alien X, but believes he is just a rumor. Ben tries to convince him that Alien X is real, but Rook doesn't believe him and asks Ben to transform and show him, which Ben refused.
 * This conversation happens again in So Long, and Thanks for All the Smoothies, and by the end of the episode, Rook sees Alien X for real, but after the universe is restored by Ben, his memory of Alien X no longer remains and he disbelieves Ben when the latter says that he used Alien X to recreate the Universe.
 * Finally, on seeing Celestialsapiens and Alien X in Universe vs. Tennyson, Rook believes Ben.
 * In Andreas' Fault, a fan of Ben refers to the Alien X smoothie as a disappointment as well as saying it tastes like "filler". This is a reference to Alien X's constant standing in the series.
 * In many promotional images and the openings to Alien Force and Ultimate Alien, Alien X is posing dramatically. This ironic, considering that he is frozen in a standing-up position for most of the time in the series proper.
 * Alien X had concept art drawn by Eric Canete, whereas his final design was created by Glenn Wong, with color styling by Chris Hooten.
 * The original plan for Alien X had him with two faces talking to represent two personalities in one body. However, because of animation challenges and the fact that Alien X has one male and one female personality, which was not reflected by the faces, the idea was scrapped.
 * Alien X was the first alien featured in Alien Force and Ultimate Alien to not be voiced by Dee Bradley Baker; the second being Rath.
 * During the entirety of Season 1 of Alien Force, the opening of the show only displayed a silhouette of Alien X because he was meant to be a surprise alien. From Season 2 onwards, the intro began showing Alien X's full image.