Benjamin "Ben" Kirby Tennyson is the protagonist of the Cartoon Network original series Ben 10. He is a child from Bellwood, who found the Omnitrix during his summer vacation with his cousin Gwen and his grandfather Max. The watch fastens on his wrist and gives him the incredible power and ability to transform into super-powered aliens, and then he uses his new powers and abilities to become a superhero, dealing with both Earth and aliens' threats, while trying to escape the alien warlord Vilgax, who pursues him relentlessly in order to retrieve the Omnitrix.
Ben has an at times contentious relationship with his cousin Gwen, bordering on sibling rivalry but also belying a ferocious loyalty between the two. Max is not only their grandfather but their mentor who once married an alien woman named Verdona (the kids' grandmother) and whose past includes many encounters with alien life.