Maxwell "Max" Tennyson, or Grandpa Max as his grandchildren call him, is the 60-year old paternal grandfather of cousins Ben and Gwen Tennyson. With a keen sense for adventure and a strange taste in food (the only topic on which Ben and Gwen are always of a common mind), 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 motor home nicknamed "The Rustbucket", which he has modified with advanced technology. The Rust Bucket is a replica of a GMC Classic Motor home.
It is revealed in Ben 10 Alien Force episode Ben 10 Returns Part 2 that he taught his grandson Ben how to ride a bike.

Personality

Max is caring, as he has done many things to protect Ben and Gwen from getting hurt. Ever since the second season, Max usually Identifies the alien species they battle.

Alternate Maxes

Ten Year Old Max

In "Don't Drink the Water", Max gets turned into a ten year old. He doesn't care about what he eats. For example, he showed Ben and Gwen his ice cream and told them something. He has brownish-orange hair.

Future Max

By the age of 80, Future Max has further modified his RV, grown a beard, and seems to have lost his arm. In its place, he uses a neuroprosthetic replica of his arm, which can also extend and transform into a laser. He still retains his caring personality.

Ultra Grandpa

In the episode "Perfect Day", because they are within the mind of Ben he transforms Grandpa Max into Ultra Grandpa and Gwen into Coyote Gwen. When he is Ultra Grandpa he looks like he's wearing the same suit as Ben except the size is for him.









Stinkmax: In "Dr. Animo and the Mutant Ray" Dr. Animo injects him Max with Stinkfly DNA, turning him into a monster.

Santa Max

Max Tennyson is mistaken for Santa Claus in Ben 10 episode Merry Christmas.

Maxgrade

In "Gwen 10", Grandpa Max turns into is version of Upgrade to battle Vilgax.

History

Max was once in the army, had joined the astronaut program, and was a "plumber" (among other things, it seems) and has been through his share of scrapes, takes his grandson gaining superpowers in stride, and supports Ben in any way he can. Ben and Gwen were ignorant of this at first, believing him to have been a literal plumber. They began questioning this after several incidents in which he displayed knowledge and skills that a plumber would not normally have; everything from military-style hand signals to a working knowledge of nuclear reactors. Max and Vilgax are also old enemies, with Vilgax even going so far as to call Max "a thorn in [his] side."
In reality, Max was indeed a plumber, but not the kind that Ben and Gwen thought he was. He was part of a government organization called "The Plumbers" which dealt with extra-terrestrial, paranormal, and other situations that many others could not handle. One of their bases was beneath Mount Rushmore. Max also holds the rank of Magister . The group was disbanded shortly after Max defeated Vilgax for the first time, suggesting that Vilgax had been largely responsible for the various incidents they dealt with. Max was to have been among the candidates eligible for the Apollo 11 mission, and would have gone were it not for other concerns.

Alien Connections

Xylene

Max is an old friend of an alien named Xylene. She had intended to send the Omnitrix to Max, but Ben found it by accident. Max and Xylene seem to have been romantically involved and work well as a team. Xylene tries to convince Max to form a partnership and travel across the galaxy with her, but Max eventually turns her down twice: the first time due to his duties as a Plumber, and the second time due to his need to look after the kids.

Verdona

Max Tennyson's Anodite wife.She had two sons Frank and Carl Tennyson with him.

Vilgax

Vilgax and Max have had a long rivalry with each other. Max thought that he had defeated Vilgax when he strapped Vilgax to a launching rocket.

Magister

Assisted him to stop the Highbreed plot.

Max Tennyson's First Appearance (60 Year Old Man)
And Then There Were 10

Max Tennyson's Last Appearance (60 Year Old Man)
Goodbye And Good Riddance

Main Relatives

• Benjamin Tennyson: Grandson
• Gwendolyn Tennyson: Granddaughter
• Ken Tennyson: Oldest Grandson (Gwen's Brother)
• Kenneth Tennyson: Great-Grandson (Future)
• Gwendolyn Tennyson: Great-Granddaughter (Future)
• Carl Tennyson: Son
• Sandra Tennyson: Daughter in-law
• Verdona Tennyson: Wife
• Devlin Levin: Great-Grandson adopted (Future)