Ben Tennyson is a kid. He's average in many ways, except for a powerful watch called the Omnitrix which allows him to become dozens of different aliens. His world the Land of Aliens was destroyed and he and his cousin Gwen were the only survivors. After this he became one of the heroes defending the universe, and he even found himself a girlfriend, Kiki Benjamin. He is brash, but he has been maturing slowly. Decides Kiki, Dani and Sari are shown to have crushes on him.
In the future, so far he appears to be one of the few heroes capable to fight Kronos one on one safely. It is mentioned he has become Rex's mentor.
His aliens worlds were once a part of the land of aliens, but have moved
Cousin Gwen Tennyson
Girlfriend Kiki Benjamin
Future son Ken 10
Keyblade & Mew powers ( on occasion )