Carl Tennyson

Carl Tennyson is the husband of Sandra Tennyson's husband and the father of Ben. He is the son of Max Tennyson and Verdona.

Ben 10
In his first animated appearance, Goodbye and Good Riddance, he was shown to resent his father, as his work as a plumber prevented him from spending time with his family. He found out about the Plumbers and the Omnitrix the hard way when Vilgax destroyed their house and held him hostage, leading to Ben (as Cannonbolt) saving him. He later assisted Ben, Gwen, and Max in defeating Vilgax, and inside a gutter, he turned a gas pipeline on and set fire to it while XLR8 saved him and Vilgax was caught in the explosion and was supposedly killed. He offered Max dinner but since Vilgax had destroyed their home he couldn't. Max told lhim that he could cook something in the Rust Bucket. Knowing Max's weird taste for food, he said that it would be better to go to some restaurant.

Ben 10: Race Against Time
In the live-action film Ben 10: Race Against Time, he is depicted as a new-age style parent who wants Ben to have his "freedom," insisting on being called "Carl," not "daddy," "dad," or "father," and letting Ben run off on mysterious adventures without asking questions. Carl wants his wife to give their son some freedom. He seems to be even more laid back than his wife, and is seen at least twice telling her to let Ben have his fun. For instance, near the end when Ben's mother tells him to not eat too much cheese, Carl says to "Let the kid live a little. Eat all the cheese you want, Ben!"

Ben 10: Alien Force
Carl later appears in the Ben 10: Alien Force episode, Grounded, where he and Sandra discover Ben's superhero activities. Apparently unable to handle the thought of their son constantly risking his life, and angered about Ben's constant lying about his activities, they ground him, forbid him from using the Omnitrix, and tell Gwen's parents of her superheroism, resulting in her grounding as well and Kevin being forced to fight the Highbreed alone.

Additionally, Carl was furious when he found out his father had something to do with it. When this proves to be too much for Kevin to handle, Ben openly defies his parents and uses the Omnitrix to turn into Humungosaur and, (literally) break out of the house and help Kevin; through this, they realize just how important Ben is to the world. They later come to help Ben and Kevin fight, (shooting a Highbreed Commander with Max's ray gun,) and admit that they are proud of Ben, openly allowing him to resume his super heroism. During this time, Carl admits that he had known all along about Max's time in the Plumbers and resented him for it, but now realizes that he was protecting them just as Ben was.

Ben 10: Ultimate Alien
Carl reappeared in the episode Hit 'em Where They Live. He was ambushed by Charmcaster, Zombozo, and Vulkanus. One of the trio flattened his car tire, disenabling him to get away. They were about to strike when Ben, Gwen and Kevin came along and saved him. He was completely oblivious that any of this was happening, even when there was confetti raining from the sky.

Trivia

 * Like his brother Frank, Carl know's about his father's secret and his mother's identity as an Anodite.
 * He appeared to be in possession of a Plumber bazooka hidden in his attic, his current residence also being his childhood home.
 * Unlike his wife Sandra, Carl is softer on Ben, up to the the point of letting him live his life. Carl seems to contradict Sandra when it comes to disciplining Ben, being more loose than stern, though like Sandra, he insisted to be called by his name.
 * In his only appearance in the original series, Carl looks like a younger, thinner version of his father Max Tennyson, but with the same green eyes as his son, Ben, his neice, Gwen, and his nephew, Ken, and was voiced by Dee Bradley Baker, while in his only appearance in the Alien Force series, Carl's appearance was modeled after his live-action film actor, Doc McManus, from the live-action film, Ben 10: Race Against Time, who also provided Carl's voice as well.
 * His eyes are green in the original series but in Alien Force his eyes are brown.
 * Given the similarity of their personalities, it is likely that Carl takes after his mother Verdona, although they have yet to be seen together on screen.
 * In the novels, his name is spelled as Karl.