Benjamin Kirby “Ben” Tennyson was a normal ten-year-old kid until he found the Omnitrix, a powerful watch-like device that allowed him to turn into ten different aliens. Though initially immature and clumsy, Ben grew to be a true hero. By the time he was sixteen, he had become famous in not only his hometown of Bellwood but on Earth and beyond. Ben has also been deputized by the Plumbers and gained more aliens as time progressed.

Ben’s physical appearance has changed throughout the series from a ten-year-old to a sixteen-year-old. However, he retains some recurring characteristics. He has shaggy brown hair, green eyes, pale skin, and he’s quite skinny for his age, though he shows a lot of muscle definition due to being athletic.

In the Omniverse flashbacks in which he was 5 years old, Ben wore green overalls with a white shirt underneath it. White numbers saying “5 1/2” were on a black square in front of his overalls.

In the original series and Omniverse flashbacks, Ben’s usual clothes consisted of a black-striped, white shirt with short sleeves, military green cargo pants with side pockets with a black belt hidden under his shirt, and black and white sneakers with black stripes. Ben wore the prototype Omnitrix on his left wrist.

In Alien Force and Ultimate Alien, Ben wore a black shirt, blue jeans and a green jacket with white stripes and the number 10 on it, white socks, and black and white Converse-style shoes. Ben wore the prototype Omnitrix in Alien Force and the Ultimatrix in Ultimate Alien on his left wrist.