Frank Tennyson

Frank Tennyson is the husband of Lily, and the father of Gwen and Ken. He was discussed in the last episode of the original series, when Gwen stated that her father got a new job and had to move and go to Ben's school. He was later introduced in the Ben 10: Alien Force in the episode What Are Little Girls Made Of?. When Gwen told him about her powers, he said he hoped that the day she met her grandmother would never come.

He apparently already knew about his father's, Max's, life as a Plumber. He does not have the "the spark" that his daughter has and that gives her her powers; however, in the episode What Are Little Girls Made Of?, Grandma Verdona states that he always knew when she was eavesdropping on him while being invisible to the human eye, suggesting he might actually have a passive ability. He also thought Gwen was going out with Kevin without telling him or her mother, with had made both blush.

Trivia

 * He is voiced by George Newbern who is best known for voicing Superman in various DC cartoons and movies.
 * He and his brother, Carl are half-human, half-anodite. However, neither of them has "the spark".
 * It is not known if he accepts the fact that Gwen and Kevin are dating like his wife does.