Gorvan

Gorvan is a renegade Tetramand plumber who abandoned his duty and started selling alien tech to the highest bidder. He first appears in Ben 10: Alien Force (Video Game) as a villain. He seems to look pretty obese, but since he's a Tetramand, he still has super strength, and even quite speedy and fit for some reason. He also uses a machine to heal himself while fighting Ben, making him pretty hard to beat. He has yet to appear in the TV series though it is unknown whether or not he will.

History
Ben first meets Gorvan where he was fighting a group of Forever Knights, where he is after a mysterious component. Gorvan enlists Ben, Gwen and Kevin's help to find the rest of the components. He claims to be a Plumber and even knew Ben's grandfather Max Tennyson. Secretly, he was working for the Highbreed and is on the run from the Plumbers. He tricked the trio into invading a Forever Knight's castle and fighting Vulkanus and his pick-axe aliens for another component. He even turned Kevin into a DNAlien and made him fight Ben, but luckily, Ben was able to defeat Kevin and change him back to normal, Gorvan then fights Ben, and used a rejuvination machine to recrease his stamina. Ben was still able to defeat him though and kept Gorvan captive with some holding-cells. It is unknown what happened to him after the game was over, though it seemed simple that he was put into Plumbers' captivity.

Trivia

 * Even though Gorvan is a video-game only character, he has his own action figure and his collective card shows what he looks like in the TV series. He also has a smaller toy in an Alien Creation two-pack with Upchuck.
 * Gorvan is the same species as Four Arms (he prefers that people call him a Tetramand and not a Four Arms).
 * Gorvan looks fat, but he still has the super strength of a Tetramand(Gorvan himself admits he could stand to lose a little weight).
 * Gorvan is smaller than most other Tetramands.
 * Gorvan is one of the few Plumbers to have gone rogue and become a criminal. Before going rogue, he held the rank of Magister, making him currently the only known Magister Ranked Plumber to have gone rogue.
 * Gorvan didn't seem to be aware of the Highbreed's true plan, like the Forever Knights were.
 * Even though the Forever Knights were allies of the Highbreed, Gorvan fought them and used Ben and his friends to attack them and steal one of their components.