Magister Maxwell "Max" Tennyson, also known as Grandpa Max, is one of the main characters of the Ben 10 series,
Max is the paternal grandfather of Ben and Gwen. He is a fairly overweight man in his late 50's, with a keen sense for adventure and a strange taste in food. Max ends up taking the kids on a summer vacations' road trip across the United States. Max travels in a motor home nicknamed the Rust Bucket, which he has modified with advanced technology.
Max was a semi-retired legendary Magister rank Plumber and is the mentor of Ben, Gwen, Kevin, and the Plumbers' Helpers. Max is widely considered the greatest Plumber in the Milky Way. As of Omniverse, Max quit retirement and joined the Plumbers again, and is currently Magister of Earth.
In the AWA fics, Max is part of the AWA and works as one of it's instructors.
In the XP4 fics, Max debuted in the XP4 Heroes Coalition - Neo-City Diaries.
In the original series, Max wore a white shirt, covered by a red buttoned-up Hawaiian shirt with a floral design. He had grey hair and blue pants, as well as brown shoes.
After being turned into a ten year old in Don't Drink the Water, Max was seen wearing Ben's regular clothes, a black-striped, white shirt with short sleeves, military green cargo pants and black and white sneakers with black stripes. His hair was also similar to a crew cut, and rather than fat, Max looks skinny and athletic.
As Ultra Grandpa in Perfect Day, he had a stereotypical superhero costume. He wore frameless blue goggles, a cyan shirt and white pants. He also donnes a white cape like Ultra Ben.
In Alien Force and Ultimate Alien, Max's appearance did not change except for his blue pants being changed to brown, he had more wrinkles, a slightly darker shirt, and whiter hair. He now wears black shoes.
In Alien Swarm, Max wore a blue Hawaiian shirt instead of a red one.
In Omniverse, Max's appearance has not changed that much except for his brown pants, which are now white. He has whiter hair, more wrinkles, and his eyes have been changed to little black dashes. His white shirt that he wore under his red button up shirt has changed to black. Also, his shoes are now grey at the top and black at the bottom.
Max cares about his grand kids, and is usually not too strict with them. He teaches them things a normal parent would teach. He is usually on Gwen's side when Ben and Gwen fight.
Max is an instructor at the Vanguard Academy.
XP4 Heroes Coalition - Neo-City Diaries
In Chapter 23, Max, alongside Bols and Van Grants, met up with Hank Hill whom is fixing the gutters of the Training Facility when they teased him about the lawn gnome. He then witnessed Hank chasing after Bols with a hand drill in hand.
Although Max doesn't have any super powers, he is very skilled in combat and can take on anyone who does have them as he is quite athletic for someone of his age. As a retired Plumber, he has access to a variety of various Plumber tools and weaponry, which he uses skillfully. Aside from that, his experience from his Plumber days made him knowledgeable on various species of aliens. He is also able to strategize well and is skilled in inventing new machines. He is telepathically connected to his lover, Verdona.
Before joining the Plumbers, Max was a United States Air Force pilot, with dreams of joining NASA and going to the moon. He was an expert at flying an F-104 Starfighter and was able to shoot down an alien spacecraft.
- Max was supposed to get the Omnitrix, but when Ben found it, his DNA was close enough to Max's that it attached itself to his wrist instead.
- Max was a Magister for at least 5 years.
- Max's cooking is a running gag throughout the franchise as most humans, (especially Ben, Gwen, and Kevin) find the cuisine to be disgusting, while aliens, (Rook, Xylene, and others) can't get enough of it.