Grandpa Max

Maxwell "Max" Tennyson is the protagonist of the Cartoon Network original series Ben 10. He is the paternal grandfather of Ben and Gwen. Despite his age, Max has shown on multiple occasions to be a highly athletic and formidable fighter. He takes his grandson Ben gaining superpowers in stride and supports him in any way he can. Max was once a candidate for the Apollo 11 mission and one of the leaders, or "Magisters", of the Plumber organization, but Ben and Gwen did not know of this at first, believing him to have been a literal plumber. They began questioning this after several incidents in which he displayed skills that a normal plumber would not normally have; from hand signals to a working knowledge of nuclear reactors. Throughout the first season, it seems that Max knows far more about aliens than he lets on, which climaxes in the season finale, where it is revealed that he and Vilgax are old enemies. Before Ben got the Omnitrix, Max tried to keep the Plumbers a secret from his family to protect them, but his plan failed when the Omnitrix and Vilgax came to Earth. Max drives a recreational vehicle nicknamed the "Rust Bucket" that conceals a wide range of Plumber weapons and technologys.