Magister Maxwell "Max" Tennyson or Grandpa Max as his grandchildren call him, is the paternal grandfather of Ben and Gwen. He is a fairly overweight man in his late 50's to early 60'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.[9] As of Omniverse, Max quit retirement and joined the Plumbers again, and is currently Magister of Earth.