Max Tennyson is a fictional character from the animated television series Ben 10. He is the grandfather of the main character, Ben Tennyson, and serves as a mentor and guardian. Max is known for his wisdom and experience, often providing guidance to Ben and his cousin, Gwen Tennyson, during their adventures. In the series, Max has a background in the Plumber organization, which is dedicated to protecting Earth from extraterrestrial threats. His character is portrayed as resourceful and knowledgeable, often sharing important information about alien technology and creatures that the young heroes encounter.