Kevin Ethan Levin is a former nemesis of Ben Tennyson and one of the main three characters of Ben 10: Alien Force. He can absorb the properties of any surface and use them to fight with, which later states him as a hybrid-osmosian. Previously, he was one of Ben's most hated rivals as he tried to absorb the power of Ben's Omnitrix. He succeeded, only to result in his human form permanently mutated into a freakish combination of all ten of Ben's aliens. He returned in Ben 10: Alien Force after being left in the Null Void since his last appearance. His DNA had later stabilized and he returned to his human self. He is now Ben and Gwen Tennyson's ally as they fight the DNAliens and enemies new and old.
Backfiring PlanTired of guerilla tactics, Kevin decided it was time he took the war directly to Fuse's lair. With the help of the Hero, he was able to collect some samples of the local Fusion Spawns, and absorbed their Fusion Matter, hoping to match Fuse's strength.
Unfortunately, Kevin's plan backfired, and Fuse gained control over him by means of the absorbed Fusion Matter. Under Fuse's control, Kevin tricked the Hero into attaching a device to Foster's Home in order to transfer Imaginary Energy to Fuse's lair in the Darklands for study. Fortunately, Dexter was able to uncover the plot, and was able to slow down the transfer and free Kevin from Fuse's control. Dexter was unable to stop the transfer completely, however, because doing so would prove fatal to the Imaginary Friends. Nonetheless, the transfer seems to have slackened after Billy got into Fusion Kevin's lair in the Green Maw. Fuse continues to use Kevin by using car keys stolen from him to produce an army of Fusion counterparts that resemble eleven-year-old Kevin's giant alien form in Fuse's Lair.
- He was changed to his design from Ben 10: Alien Force Season 3.
- He is one of few characters that players are able to fight.
- His fusion is on his mutated form instead of his human form.
- Fuse was still able to create Kevin's "11" Fusion counterpart with Kevin's which he got when he was eleven years old.