Maxwell "Max" Tennyson who is portrayed by Lee Majors, or Grandpa Max as his grandchildren call him, is the 60-year old, rather overweight and a bit slow at times, paternal grandfather of cousins Ben Tennyson and Gwen Tennyson. With a keen sense for adventure and a strange taste in food (the only topic about which Ben and Gwen never argue), Max always ends up taking the kids on interesting trips. As soon as school lets out, Ben looks forward to going on a traditional summer road trip with Max. Much to Ben's annoyance, Ben discovers that his cousin Gwen (whom he dislikes) is joining them as well. Max travels in a motorhome nicknamed "The Rust Bucket", which he has modified with advanced technology. The Rust Bucket is a replica of a GMC Classic Motor home. In the live action Ben 10 film, Max is played by Lee Majors.
The Plumbers "(that's why your grandchildren think it's just a plumber) and it is revealed that Max and Vilgax are old enemies. But the grandfather also has a companion who then turned against him by easy money, unlocking and fighting the aliens who had already captured. Also in the episode "The Return" Max reveals that should be the first man on the moon. Besides the Omnitrix was addressed to Max (the part of Xylene, of which he has a crush ) and not for Ben, but the latter is found.
By the age of 80, Max has further modified his RV, grown a beard, and lost his arm in the Limax Wars of 2018. In its place, he uses a neuroprosthetic replica of his arm, which can also extend and transform into a laser, and a large array of other weapons Further in the future (now 92), around when his great grandson Ken is 10, Max has lost his beard and much of his weight and height, which was explained as being due to his age and a steady diet of futuristic health food.This is non-canon.
Ben 10: Alien ForceEdit
In Ben 10: Alien Force, Max looks mostly the same as before, save for more wrinkles and whiter hair. He leaves a transmission for Ben stating that he is investigating renewed alien activity on Earth and claims (erroneously) that he has the Omnitrix. An image of a DNAliens flickers at the end of the transmission. He appeared dead when a null void detonator he had planted blew up, but was instead sent to the Null Void, where he, calling himself "The Wrench," fought Dr. Animo, who was calling himself DeVoid. He has since appeared in the two parter "War of the Worlds" to aid Ben in his battle with the Highbreed along with the "Plumber Helpers". At the end he takes many Plumber children under his wing as his apprentices.
- He had the same shirt in all the episodes of Ben 10 at years of 60, 80 and 92.