Ben was a ten-year-old boy who grew up in Bellwood; he was unpopular to his classmates and often bullied in school by two boys named Cash and J.T. However, his life changed the day he went on summer vacation with his grandfather, Max and his cousin, Gwen. That evening, they stopped to camp in the woods. Ben witnessed the crash of a strange capsule from space, which happened to contain the Omnitrix, a powerful watch-like device.
As soon as Ben found the device, it firmly affixed itself onto Ben's left wrist, and Ben was unable to remove it. At first scared, Ben soon discovered that, using the Omnitrix, he was now able to transform into ten super-powered alien creatures, and began to use the device to become a superhero. Though he occasionally arrested ordinary criminals, he was quickly led to also fight super-villains, starting with Dr. Animo, Kevin 11, and ultimately, Vilgax, a vicious and evil alien warlord who would stop at nothing to get the Omnitrix for himself.