|This article belongs to the Classic Continuity|
Carl has fair skin, brown eyes, and brown hair.
In the original series, he wore a green polo shirt, a brown belt with a gold buckle, khaki pants, and brown shoes.
In Alien Force, he wears a white dress shirt, brown pants, and the same shoes.
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Carl has known about the Plumbers since he and Frank were kids, and is seriously torn up by his father's association to them.
When Ben mentions that the watch was initially intended for Max, Carl transferred his anger to his own son, once he sees the same pattern of behavior cropping up again.
Carl chronologically first appeared in Destroy All Aliens, where he and Sandra ground Ben for not telling them where he went as well as for the mysterious footprints that were on the floor and a mishap in Ben's school where the Omnitrix accidentally teleported his homework. They forced Ben to stay home and complete a history report. Later on, Carl and Sandra inform Max and Gwen that Ben has escaped the house and Grey Matter enters into their house where Carl and Sandra discover the creature. After Sandra begins attacking Grey Matter, he is thrown outside and transforms into Diamondhead. Sandra passes out and Max knocks Carl. Afterward, the Omnitrix malfunctions and transforms him into Wildmutt and transforms Sandra into Heatblast. Eventually, Gwen and Ben use the Omnitrix to transform him and Sandra back into normal and they, having forgotten that they grounded Ben, allow for Ben to go on a fishing trip with Grandpa Max and Gwen.
Carl first appeared in Grounded, where he and Sandra end up getting caught in the middle a Highbreed's nighttime rampage while driving into downtown Bellwood, and discover Ben's superhero activities at the same time when they catch him transforming into Swampfire to fend off the alien. Apparently unable to handle the thought of their son constantly risking his life, and upset with him for hiding his activities from them for five years, 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 outraged to learn that the Omnitrix was initially meant for his father.
When the mission proves to be too much for Kevin to handle, Ben openly defies his parents and uses the Omnitrix to turn into Humungousaur and, (literally) break out of the house and help Kevin; through this, they realize how important the things Ben is doing really is. They come to help Ben and Kevin fight, and admitted that they are proud of Ben, allowing him to resume his 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.
Carl reappeared in Hit 'Em Where They Live. He was ambushed by Charmcaster, Zombozo and Vulkanus. They flattened his car tire, making him unable to escape. They were about to strike when Ben, Gwen and Kevin came along and saved him. He was completely oblivious to what was happening.
- Ben 10: Destroy All Aliens (first chronological appearance)
Ben 10: Alien Force
- Grounded (first appearance)
Ben 10: Ultimate Alien
- Hit 'Em Where They Live (first reappearance)
- The Ultimate Enemy: Part 2 (flashback; cameo)
Cartoon Network Action Packs
- Carl and Sandra approve of Ben's friendship with Rook.[DJW 1]
- Like Frank, Carl knows about his father's secret and his mother's identity as an Anodite. However, they only found out about the latter when they were adults.[DM 1]
- Carl and Sandra are much less conservative than Frank and Natalie.[DM 2]
- Carl has a Plumber bazooka hidden in his attic, his current residence also being his childhood home.
- In the novels, Carl's name is misspelled "Karl".