Kevin Levin (Classic)

Kevin 11 by all outward appearances a rebellious teenager, Kevin (voiced by Michael Reisz in his first appearance and Charlie Schlatter in his following ones) is actually a sociopath that Ben meets after having an argument with his grandfather. Kevin is a mutant with the ability to absorb any type of energy and release it at will. The energy can be used to activate or overload various machines and can also be used to make energy blasts. When absorbing energy from the Omnitrix's aliens, he becomes an incomplete, but effective, version of that alien. In his first appearance in "Kevin 11", he absorbed the abilities of Heatblast and Fourarms, using the former form's powers to get revenge on those who had wronged him. He absorbed the later form's powers during his second battle with Ben to even the odds. After trying to take the Omnitrix from Ben, the Omnitrix emitted a feedback pulse to prevent Kevin from taking it, seemingly neutralizing his power. Kevin, however, exhibits the ability to create flame at the end of the episode.

Kevin serves as the main antagonist of the second season. His ability to project heat at the end of "Kevin 11" is a result of the Omnitrix's feedback pulse: the amount of energy it emitted allowed him to fully absorb its powers, giving him access to every alien form Ben had at the time. As a side effect, however, Kevin's ability to regulate this power is poorer than that of the Omnitrix itself, causing the energy to suppress his human form and forcing him to remain as an alien most of the time. As revealed in "Framed", Kevin blamed Ben for this, so he uses the powers of the Omnitrix to commit crimes, both for his own benefit and to damage Ben's (or rather, his alien forms') reputation. Eventually, Kevin's ability to regulate the power fails altogether, causing him to permanently mutate into what Vilgax would describe as a "misshapen, chaotic amalgam of creatures from the Omnitrix."This form has:


 * Fourarm's head, body, left eyes and legs
 * Grey Matter's right eye
 * Upgrade's upper back
 * Stinkfly's wings
 * Diamondhead's right arm
 * Heatblast's left arm
 * Wildmutt's arms below them
 * Ghostfreak's lines
 * XLR8's tail
 * Ripjaw's' antenna, gills, and teeth

After a brief battle with Ben as Fourarms, Kevin is shot off the Golden Gate Bridge by a laser fired by one of Lt. Steel's men.

After his mutation, Kevin gloats that he has all of Ben's powers plus his own, making him "Kevin 11" (the name Kevin is credited under in the ending sequence of the show). Despite Kevin's claim, Ben notes that Kevin's powers aren't as good as his pure version (he quips that they're only one-tenth as strong, though this is likely not an accurate assessment), and Kevin never exhibits his original powers in this form, nor those of Ghostfreak, Grey Matter, or Upgrade. Kevin's mutated form also limits his ability to use the special powers of his alien forms. Being a random fusion of aliens, Kevin only has access to the powers most prevalent in his form. In addition to these limitations, Kevin seems unable to use the powers of any aliens Ben has gained since their original encounter.

During his third appearance in "Grudge Match", Kevin attacks Ben to get revenge, blaming his condition on Ben. As the two battle, they are abducted and forced to fight in gladiator games. During their battles, Ben helps Kevin to realize the advantages of his mutated form. Because Kevin is an amalgam of aliens, he can mix and match their powers to make up for their reduced potency. Although forced to work together, Kevin's only goal was killing Ben. He is transported to a different galaxy at the end of the episode while locked in combat with Technorg.

Kevin returns in the episode Back With a Vengeance, where he teams up with Vilgax to defeat Ben, and eventually manages to remove the Omnitrix. However, he betrays Vilgax later in an attempt to leave both in the Null Void, only for Ben to escape and leave him and Vilgax trapped instead.

In "Ken 10", Kevin returns after at least thirty years of imprisonment in the Null Void, having been set free by his son, Devlin. Kevin has now fully mastered his powers and can return to his human form. In his human form, he can also utilize the powers he has absorbed to a limited extent, such as XLR8's speed. His mutated form, though still an amalgam, has changed considerably from his continued absorption of alien DNA, leading to his new title of "Kevin 11,000". He still has Wildmutt's arms, Stinkfly's wings, and Fourarms' legs, he now has:

Eager for revenge and having not so much as a care for his son, despite Devlin's role in releasing him, Kevin proceeds to beat on Ben and his son, Ken. Ironically, it is Devlin who stops him, trapping his father back in the Null Void.
 * A Heatblast-like head, body, left wing and right tentacle, but black instead of red.
 * A left tentacle that splits in the middle into a Fourarms' arm and a tentacle with Upgrade and XLR8 tail markings
 * Several grey tentacles (similar to the tentacles of the flying aliens featured in "Truth" and "Back With a Vengeance") protrude from his lower body.
 * He also is able to send out sonic howls similar to that of Benwolf
 * Wildmutt's arms
 * Stinkfly right wing
 * Fourarms' legs

In the video game Ben 10: Protector of Earth, Kevin only appears, surprisingly, as a mini-boss Ben fights at the end of Lumber Mill.