Kevin Ethan Levin | Ben 10

Kevin Ethan Levin (voiced by Michael Reisz in his first appearance, Charlie Schlatter in his following ones, and by Greg Cipes in Ben 10: Alien Force) is a human-alien hybrid with the ability to absorb any type of energy and release it at will, though he seems only able to release electricity, or he may simply favour this due to it's offensive potential. The energy can be used to activate or overload various machines and can also be used to make energy blasts. 

Kevin Ethan Levin
Statistics
Voice Actor:	Michael Reisz/Charlie Schlatter (Ben 10) Greg Cipes (Alien Force/Evolutions)
Age:	11 (Ben 10) 16 (Alien Force) 17 (Evolutions) 41 (Future)
First Appearance:	Kevin 11
Affiliations:	Ben's Team Plumbers (loosely) Himself (formerly)
Occupation(s):	Hero Conman (Formerly)
Abilities:	Matter Absorbtion Energy Absorbtion (formaly?/unused?) Possible Genetic Material Absorbtion
Relative:	Unnamed father Unnamed mother Gwen Tennyson ("girlfriend")
Alias:	Kevin 11 (formerly)

Kevin before mutating
 

Kevin was abandoned before the start of the series due to his powers, and has been alienated ever since, this has lead to him developing anti-social behavior disorders that border on sociopathy, however, he is reformed over the course of Ben 10 Alien Force, and rejoins society and apparently recociles with his family. 

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 is first encountered by Ben Tennyson in an arcade, where he was assaulted by bullies and saved by Ben as XLR8. The two attempt to steal video games from a warehouse and get caught by the police, forcing Ben to reveal his powers to him in order to escape.

Eventually, Ben breaks off their partnership when Kevin rigs two trains (one carrying money) to collide in, not caring that hundreds of innocent people would be killed. He then 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 latter 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 after his mutation

 

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.

However, because Kevin's ability to regulate this power is poorer than that of the Omnitrix itself, the energy suppresses his human form and forces him to remain as an alien most of the time. As revealed in "Framed", Kevin blamed Ben for this, so he used the powers of the Omnitrix to start a crime spree in Los Angeles, 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, and Ripjaws antenna, gills, and teeth. 

 

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). He has Stinkfly's ability to fly and his slime spitting. Diamond Head's diamond ability with his right arm. Fourarm's strength. Wildmutt's sniffing ability. XLR8's speed.

Heatblast's ability to shoot fire out of his left arm. Ripjaw's bitting (possibly also his ability to breath under water because he has Ripjaw's gills). Although Kevin does not have all of the powers of the omnitrix aliens he copied. He does not have Grey Matters intelligence, Upgrade's ability to take control machines and his lazer vision, and Ghostfreak's ability to turn invisible and his ability to walk through walls.

Despite Kevin's claim, Ben notes that Kevin's powers are only one-tenth as strong, (although this assessment may not be accurate) and Kevin never exhibits his original powers in this form (the same is true for Ghostfreak, Upgrade (though this is debatable when Kevin used XLR8's tail to slam a tray of Megacruiser food into Technorg's face), Grey Matter, or Wildmutt. 

Kevin's 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 Slix Vigma's gladiator games. During their battles, Ben helps Kevin to realize the advantages of his mutated form. Because Kevin 11 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, who beat him then escaped. He then took the ship as his own.

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 and use the Omnitrix to take over the world, only for Ben to escape and leave him and Vilgax trapped instead.