Ben Tennyson was a normal ten-year-old kid until the day he found the Omnitrix. Once he put on this mysterious alien device, he couldn't take it off. The Omnitrix gave Ben the power to transform into ten different alien life-forms, and whether he wanted to or not, Ben became a superhero.
With the help of his Grandpa Max and Gwen, Ben defeated Vilgax, an alien warlord determined to rule Earth. Ben continued to fight to defend the Earth but before he turned eleven he found a way to remove the Omnitrix. His life went back to normal - for a while.
The Omnitrix is a mysterious watch-like alien device that allows the user to transform into various alien forms by combining the DNA of the selected alien with the user's own DNA, effectively turning them into the alien species the user has selected. The alien form is selected by unlocking the control dial, turning the control dial to the desired alien species which is displayed on the Omnitrix's display, then pressing the control dial back into place completing the transformation. The alien DNA also seems to contain some aspects of the original aliens' personality; when questioned how it felt to be an alien, Ben described it as follows: "It kinda freaked me out at first. It was like I was me...but it was also like I was somebody else." 
The Omnitrix was originally created by Azmuth to allow the people of the universe a way to "walk in someone else's shoes". However, many beings saw the Omnitrix's abilities(U) as something that could be used as a powerful weapon—,most prominently the villain Vilgax who claims it to be the most powerful weapon in the galaxy. Fearing that people might misuse the Omnitrix for this very reason, Azmuth put several safeguards in place to ensure that whoever used the Omnitrix would not have full access to its powers. Several of these safeguards include transforming into an alien different from the one that is selected on the control dial, the ten minute auto time-out, the restriction of only ten accessible aliens, and a self-destruct mechanism. However, these safeguards are disabled once the Master Control for the Omnitrix is unlocked, which is apparently done by a random combination of selections on the control dial. Once the Master Control is unlocked, the user can stay in their alien form indefinitely and is also able to switch between alien forms at will just by thinking about it, speaking the name its user has given any alien, or turning the badge with the Omnitrix insignia on it.
In addition to the aliens that were pre-programmed into the Omnitrix's DNA sequencer by Azmuth, the Omnitrix also possess the ability to absorb DNA samples from other alien species by simply coming into contact with them, effectively downloading a DNA sample and allowing access to that alien form. Also, the omnitrix may automatically correct any broken DNA samples that are extracted, however, this phenomenon was not seen in the original Ben 10 series, but in the sequel Ben 10 Alien Force.
The first is a regular animated feature called Secret of the Omnitrix. A trailer of the film was released with the film Billy & Mandy: Wrath of the Spider Queen, and it aired August 10, 2007. Michael Ouweleen described the film's villain, which was actually Vilgax, as "like Darth Vader without the sense of humor." A different version of Secret of the Omnitrix, which introduced a different alien (Eye Guy) to the one in the original (Heatblast), aired on September 1, 2007. A third version (in which XLR8 was featured) aired on October 34, 2007. It was stated during the premiere of Alien Force that Secret of the Omnitrix was intended to be the chronological finale of Ben 10, even though it was broadcast long before the last episode, which was not canon.
The second is a live-action film titled Ben 10: Race Against Time which aired November 21, 2007. The plot presumably takes place before Goodbye and Good Riddance, it revolves around Ben, Gwen and Grandpa Max returning to their hometown of Bellwood and attempting to adjust to being 'normal' again. Unfortunately, their lives are once again disrupted by a mysterious alien known as Eon, who has an unexpected connection to the Omnitrix. It premiered on Cartoon Network on November 21, 2007. The film was directed by Alex Winter. Winter stated at the 2007 upfront presentation that he wanted "this thing to look like X-Men," an epic adventure that will be "more cinematic than cartoony" and appeal to all ages. Production on the film finished in October and premiered November 21, 2007. Ben 10: Alien Swarm a sequel to Race Against Time premiered November 25, 2009.
Main article: Ben 10: Protector of EarthThis is the first Ben 10 video game, released in Autumn 2007.
Following the success of the Ben 10 animated TV series and films, various Ben 10 merchandise has been released for general sale. These items include Ben 10 books, action figures, card games such as Top Trumps, toys, video games - notably Ben 10: Protector of Earth, bedding, and footwear.
Main article: Cartoon Network Universe: FusionFallBen 10 appears in Cartoon Network's online MMO FusionFall. The character design for Ben Tennyson was changed when the original Ben 10 series ended and was replaced by Ben 10: Alien Force. In the game, he serves as a "Player Guide" offering guide-based missions and special items that can only be used with certain
- Ben 10: Race Against Time
- Ben 10: Protector of Earth
- Ben 10: Alien Force
- Ben 10: Ultimate Alien
- Ben 10 (toy line)
- Lego Ben 10
BEN 10 ALIENS