Mikail Minat Ben 10

The Omnimatrix (often referred to as the Omnitrix) was a watch-like device which attached to Ben's wrist in the first episode of the series and is the device that the series revolves around.

The Omnitrix was created by Azmuth as a tool of peace in an act of repentance following the destruction caused by his previous creation, the Ascalon. The device had a twofold purpose: it would promote inter-species understanding by allowing other beings to experience different ways of life, and it would also serve as a repository for the DNA of millions of species, preserving them in the event that any of them should ever become extinct. Secretly, Azmuth also had a another reason for creating the device: he hoped his estranged lover Xeneth, who had left him after he created Ascalon, would learn of his newfound altruism.

The Omnitrix had been destroyed in The Final Battle: Part 2 in order to prevent Vilgax from using it and replaced by the Ultimatrix.

In Map of Infinity, Azmuth reveals he is creating a third and superior Omnitrix. However, he refuses to give it to Ben as Ben's maturity has lately regressed considerably, making him more reckless and impatient, and it was incomplete anyway.

Benjamin Kirby Tennyson was an average 10-year-old kid, until he found the Omnitrix, an exceedingly strong and powerful watch-like device that allowed him to turn into ten different alien species. Though initially immature and clumsy, he grew as a true hero, who, by the time he was sixteen, had become famous in not only his hometown of Bellwood, but on Earth and beyond, as well as a member of the Plumbers. 

Physical Appearance

Ben's physical appearance has evolved throughout the series from a ten-year-old to a fifteen and sixteen-year-old teenager. However, he retains some recurring characteristics. He has short brown hair, green eyes, pale skin, and he's quite skinny for his age (though his various future selves are portrayed as quite muscular), though he shows a lot of muscle definition due to being athletic. In the original series, his usual clothes consisted of a black-striped, white T-shirt with short sleeves, deep green cargo pants, and black and white sneakers. Starting with Alien Force, he starts wearing a black T-shirt, blue skinny jeans and a white-stripped green jacket with the number 10 on it, clothes he retains in Ben 10: Ultimate Alien. Ben wears the Omnitrix and Ultimatrix on his left wrist in a watch-like manner. Like all the other main characters, his physical appearance hasn't changed much.

When the cross over special with Generator Rex occured, Ben's appearance changed according to the animation of that series, becoming sleeker and more mature in appearance.