ben 10

10-year-old Ben Tennyson finds an alien device out in the woods, the Omnimatrix (Omnitrix for short), which allows him to turn into ten different alien species, Heatblast, Wildmutt, Diamondhead, XLR8, Greymatter, Fourarms, Stinkfly, Ripjaws, Upgrade and Ghostfreak. Throughout his summer vacation, traveling the country in the "Rust Bucket" with his Grandpa Max and his cousin Gwen, Ben fights crime and evil aliens with his new powers, gaining the ability to turn into 10 more aliens, Cannonbolt, Wildvine, Benwolf, Benmummy, Benvicktor, Ditto, Upchuck, EyeGuy, Waybig and Eon who was in "Ben 10: Race Against Time."

Alien Force

Main article: Ben 10: Alien Force

Five years after the original series, Ben has apparently taken off the Omnitrix, but when his Grandpa Max goes missing, he puts it back on, which reboots it and gives Ben a new set of ten aliens. Ben's old enemy, Kevin Levin, somehow escaped the Null Void, but has become (mostly) reformed and joins Ben's team. Ben has Swampfire, Echo Echo, Humungasaur, Jetray, Big Chill, Spidermonkey, Goop, Brainstorm, Chromastone, and Alien X.

Ultimate Alien

Main article: Ben 10: Ultimate Alien

Several weeks after the end of Alien Force, Ben now has the Ultimate Omnimatrix/Ultimate Omnitrix/Ultimatrix, which allows him to 'evolve' his aliens into more powerful forms. Even though it was advertised that Ben now has all of his old forms, this doesn't really happen until Ben 10,000 Returns.