Ben 10 is a show about a boy named Ben Tennyson, who is on a camping trip with his grandpa. While getting ready for bed, Ben sees a comet crash in the distance, and wants to investigate. His cousin, Gwen, tries to stop him, but Ben doesn't listen to her. At the crash site, Ben finds a strange watch (the Omnitrix) and puts it on. The watch won't come off once he puts it on. When he tries to set it, he turns into an alien. He manages to change back by trying to set it again. He figures out that the watch allows him to turn into 10 (there are more coming) different alien "super-heroes". He soon becomes "on the run" from an alien named Vilgax, who wants to take over the planet with an army of omnitrix wielding clones. To do that, he needs the omnitrix.
Omnitrix Aliens from Ben 10
There are many aliens in the omnitrix. These are the main ones: