Ben Tennyson

Ben Tennyson is the main protagonist of all 3 Ben 10 series: Ben 10, Ben 10: Alien Force, and '''Ben 10: Ultimate Alien. '''He was just an ordanary Person prior to the start of the original series, until he found an alien device called the Omnitrix and uses it from the original series to Alien Force. Ben destroys the Omnitrix in Alien Force final episode, The Final Battle: Part 2, in order to prevent his nemesis, Vilgax, from taking over the Earth. He later then replaces it with the prototyped Ultimatrix.

Ben 10.

Ben was an ordanary kid until he spent the summer with his Grandfather, Max Tennyson, and his cousin, Gwen Tennyson, when he found the Omnitrix. After he started to use the Omnitrix, Ben had to deal with various threats, crime, people wanting to steal the omnitrix, and his most greatest threat of all: Vilgax. He later learns that the Omnitrix was created by an alien named Azmuth (in Ben 10: Secret of the Omnitrix).

Ben 10: Alien Force.

Five years after the end of Ben 10, Ben was back to his ordanary human life. After a soccer game that he won, he went to his Grandpa Max's "Rustbucket" (his RV), and found him not there. After finding out that he was missing he once again donned the Omnitrix. It recalibrated and Ben received 10 new aliens: Swampfire, Echo Echo, Humungousaur, Jetray, Big Chill, Chromastone, Brainstorm, Spidermonkey, Goop, and Alien X. After once again using the Omnitrix, He, Gwen, and his former nemesis, Kevin, went on a mission to find Grandpa Max and stop an invasion from an alien race known as the Highbreed. After defeating/saving the Highbreed, his arch nemesis, Vilgax, returns from an unknown way and wants revenge on Ben for throwing him into outer space. Later, Ben had to destroy the Omnitrix to avoid Vilgax ruling the Earth and destroying his hometown. After his battle with Vilgax, Ben then received the Ultimatrix, which has the powers to evolve his aliens into their Ultimate Forms.

Ben 10: Ultimate Alien.

Starts where Alien Force had left off. Ben (now 16) is now a world known superhero after his Alter Ego has been reveiled by a boy named Jimmy Jones (who is a long time fan of Ben). Ben and his friends go to Jones' house to find out why he reveiled his ego. The reason was that Jimmy thought that Ben would like the money and attention. Ben is now fighting a news reporter, Will Harangue, and an Osmosian warlord called Aggregor. He still uses the Ultimatrix from the end of Alien Force and it also has the power to turn Ben into every alien he has turned into all his life (i.e. Chromastone, Four Arms, Heatblast, etc).