Family Members

Ben Tennyson-The main hero of the series. He can turn into many different aliens.
Gwen Tennyson-Ben's cousin. Is a powerful sorceress.
Maxwell Tennyson-Ben and Gwen's grandpa. An intergalactic police officer, or a "plumber".
Carl Tennyson-Ben's dad. Works on the gas lines in Bellwood.
Sandra Tennyson-Ben's mom.
Frank And Lily Tennyson-Ben's aunt and uncle, Gwen's parents
Ken Tennyson (Ben's Son)-Ben's future son.
Gwen Tennyson (Ben's Daughter)-Ben's future daughter.
Devlin Levin-Ben's adopted future son.
Kenneth Tennyson(Gwen's Brother)-Ben's cousin and Gwen's brother
Wes Green-Ben's Grandfather In Law
Kai Green-Ben's future wife.
Vera Tennyson-Ben And Gwen's Aunt, presumably Max's sister.
Manny Tennyson-Ben And Gwen's uncle.
Jedidiah Tennyson-Is the uncle of Max Tennyson.
Verdona Tennyson-Ben and Gwen Tennyson's alien grandmother and Max Tennyson's wife.
Joel Tennyson-First human to be married to a Sludgepuppy.
Betty Jean Tennyson-Wife of Gordon Tennyson, mother of Joel Tennyson.
Gordon Tennyson-Husband of Betty Jean Tennyson, father of Joel Tennyson.
Camille Mann-Husband of Joel Tennyson
Lucy-Cousin of Camille Mann
Mr. and Mrs. Mann-Sludgepuppy father and mother of Camille. They did not approve of Camille and Joel's marriage, so attacked the wedding. They were battled by Gordon, Betty Jean, Max, and Gwen Tennyson. Also Camille and Heatblast, and fortunately, Heatblast turned them into a statue.

Family Pets

Ship-Ben's pet Galvanic Mechomorph that ran away at the end of Ben 10 Alien Force episode Pier Pressure.
Ben's Dog-Ben's German Shepard
Ken's Stone Puppy-Is Ben's future son Ken's pet stone puppy in the future in Ben 10 episode Ken 10.

Family Friends

Kevin Levin-Gwen's boyfriend, can absorb any solid object he wants.
Xylene-Max's plumbing friend
Magister-A fellow Plumber to Max, Ben, Gwen, and Kevin.
Phil-Max's ex-friend
Billy Alien-Ken's friend
Donovan Grand Smith-Max's friend
Edwin Grand Smith-Helped Ben and Gwen fight the Bermuda Triangle Aliens

Family Vehicles

The Rustbucket I-The first RV owned by Max Tennyson that is equipped with various high-technology. The Rustbucket I was destroyed.
The Rustbucket II-The second RV owned by Max Tennyson that is equipped with various high-technology.
The Awesome Mobile-Ken's car.

Members of the Tennyson Family have appeared in many episodes in Ben 10 And Ben 10: Alien Force.