Ben 10 characters
As soon as school lets out, Ben looks forward to going on a traditional summer road trip with Max in a motorhome nicknamed "The Rust Bucket", which Max has modified with advanced technology. The Rust Bucket is a replica of a GMC Classic Motorhome. In the live action Ben 10 film, Max is played by Lee Majors.
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; he 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. 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, 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 extraterrestrial, paranormal, and other situations that many others could not handle. Their base was beneath Mount Rushmore. 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.
By the age of 80, Max has further modified his RV, grown a beard, and lost his right arm in the Limax Wars of 2017. In its place, he uses a neuroprosthetic replica of his arm, which can also extend and transform into a selection of futuristic 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; in this future, his cybernetic arm appears far more mechanical, as opposed to before, when it appeared to be an exact replica of his original arm.
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.
In Ben 10: Alien Force, Max looks mostly the same as before, save for a couple of minor wrinkles and whiter hair. He disappears shortly before the start of the series, leaving only a holodisc with a message for Ben. In the message, he states that he is investigating renewed alien activity on Earth and that Ben need not worry. A follow-up message erroneously claims that he has the Omnitrix, followed by an image of a DNAlien flickering at the end, possibly meaning that the message (the part about the Omnitrix, at least) was recorded by a DNAlien, perhaps the one that Ben confronted in the Rustbucket. In "Kevin's Big Score", Kevin tracks down a second holodisc containing a message from Grandpa Max. This one, while still cryptic, does not contain any hints of deception as the first does. In it, Max advises Ben to form a team to fight the alien threat, recommending that he track down other child Plumbers. He appears in person in "Max Out", where he infiltrates a Highbreed factory to rescue Ken Tennyson (Gwen’s brother, not Ben's future son), and is captured by him, partially mutated into a DNAlien. He is reunited with Ben and Gwen when they come to free him. In order to stop the factory from mass-producing DNAliens, Max uses a Null Void Projector (minus the focusing lens) as a hand grenade to destroy everything within a half-mile radius, sacrificing himself in the process. However, it is debatable whether or not Max is truly dead; as he is shown to live to an extremely advanced age in the "Ben 10,000" future of the original series, it is possible that he is still alive and merely in hiding for the time being.