Benjamin Kirby Tennyson is the wielder of the Alientrix (later Biomnitrix) and the main character in Ben 10: Hero of All Ages.
Ben is now cold, ruthless, merciless and willing to put someone down. Instead of transformations he now sometimes uses weapons, his favorite weapon is an assault rifle. When both his wife and his two children dead Ben is mentally unstable. To make matters worse, he was the one to kill his son. Ben now watches over Ship and cares for him. Also, he is in love with Ester, but Ester wants to take things slowly. Ben's best men are Kevin and Rook.
In the episode Dagger on the Doorpost Ben had his ear chopped off then eaten by an rogue Citrikayah named Zukko.
In The Green Knight, Give an Inch Take a Mile, and When the Stars Align, Ben's wife and children die. Ben is shown to have been seeing things, having tantrums and unconscious from to much alcohol.