Kevin Levin (Classic)

Kevin Ethan Levin is a human-alien hybrid with the ability to absorb any type of energy and release it at will.

Dwayne McDuffie, one of the Alien Force writers, has confirmed that Kevin is in fact half-human and half-alien, (an Osmosian to be precise).

Original series
Kevin first appears in the episode Kevin 11. He reveals he was abandoned by his parents before the start of the series due to his powers, and has been alienated ever since; this has led 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 reconciles with his family. When absorbing energy from the Omnitrix's aliens, he becomes an incomplete, but effective, version of that alien.

Kevin is first encountered by Ben 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, 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 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: Fourarms' 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 feet, 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),and Upgrade's laser vision. Although Kevin does not have all of the powers of the Omnitrix aliens he copied. He does not have Grey Matter's intelligence, Upgrade's ability to take control machines, 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, as seen when Diamondhead was able easily catch and crush with his bare hands, the Petrosapien projectiles Kevin fired at him (although this assessment may not be accurate) and Kevin never exhibits his original powers in this form.

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.

Alien Force
Kevin, as mentioned by JT, is now reputed as "the toughest kid in town", indicating that he has taken up residence in Bellwood although this has never been explicitly stated, nor is it mentioned how he could've escaped the Null Void. It is worth noting that when Ben first defeated Kevin, he offered Kevin to join their group; a similar thing happened at the beginning of Alien Force, when Ben defeated Kevin as Swampfire and he was once again offered to join them, this time he took it.

In Darkstar Rising, he reveals that his father was also a Plumber. He never met his father, but his mother told Kevin stories about what his father did. This is a big gap in the original series because in Ben 10, he said that his parents both left him because of his strange electrical powers but it may have only been an exaggeration on his part, since it is slightly hinted that Kevin's mother remarried, due to him saying, "My father... my real father." It's is also possible that after the death of his father, his mother couldn't cope and Kevin then somehow ended up in foster care, and that it was these parents that left him.

At the end of the same episode, Kevin, along with Gwen and Ben become official Plumbers, after which, Kevin leaves to tell his mother about his membership, this suggests that he has now reconciled and rejoined with his family. In Darkstar Rising, when explaining that he wanted to be a Plumber for the sake of being just like his father, it "mostly" served as the reason that he joined the Tennysons in the first place. (His promise to Magister Labrid and Gwen could be the other reasons); Dwayne Mcduffie confirmed that Kevin was actually kicked out from his home after a violent incident with his parents.

In the season 3 premiere, Vengence of Vilgax, Kevin is subjected to feedback from the Omnitrix after Ben tampers with it. Because of this, he is unable to revert back to his normal human form, instead becoming a mixture of different elements. In Busy Box the box is stronger than Kevin which means it is unknown if this made his body become a mixture of the elements he has absorbed or if this fused the materials around him to his body, though it's most likely the former.

Throughout the series he is shown to hate what he was become, to the extent of breaking things off with Gwen wearing an I.D. Mask in public to appear human, and considering himself a monster. He also discovers that his father, an Osmosian Plumber, was murdered by an alien criminal, and becomes bent on vengance, relenting only at the last moment, (though the criminal, Ragnarok, still does not survive.) This episode confirms that he has reconciled with his mother at least, and that he has few momento's of his father.

In the season finale, where Vilgax attempts to separate Ben from his friends, he is kidnapped by Albedo in an attempt to split them up. He is also asked by Ben to back him up when taking on Vilgax, which he does. After Ben's Omnitrix is destroyed, he reverts back to human form, as it was the Omnitrix's power that kept him that way, and he and Gwen share their first kiss on-screen.

Alien Swarm
In Alien Swarm the Live-Action movie, Kevin is seen driving around with his car. The car is a green 2009 Dodge Challenger. Also he is seen in his human form, with his Season 1-2 clothes and regular absorbing powers. It was revealed in If All Else Fails, that Kevin's father was named Devin a and that Max Tennyson used to know him. He is also become very muscular. Whenever he's shirtless, it reveals huge arms, big pecs, and slight abs.

Possible Future
See Kevin 11,000.

Kevin's Abilities
Kevin's abilities have somewhat changed through out the course of the series. Generally, his power revolves around absorption. In Ben 10, Kevin can absorb energy and manipulate machinery to a minor extent though the energy he uses is finite, so is required to steal more. By absorbing energy from the Omnitrix, Kevin can temporarily take on attributes of any alien form Ben has currently taken on.

In "Framed", it is revealed that Kevin is able to assume any of Ben's alien hero forms at will, due to having absorbed enough sufficient energy from the Omnitrix. Despite this advantage over Ben, he is still defeated. The rage causes his absorption power to spiral out of control, mutating him into a hulking behemoth fusion compromised of the ten starter Omnitrix aliens with no way to revert back to human form, minus Ghostfreak. He remains in this form for the remainder of Ben 10. According to the enhanced version of "Framed" Kevin's human DNA restores through time. So, after 5 years he will become a human again.



In Ben 10: Alien Force (5 years after the Ben 10 series), Kevin returns in human form with his absorption powers intact. However now, he is able to absorb the properties of material into his own being such as metal or rock, transmuting himself a living form of whatever material he has absorbed and use it to increase his physical strength. Kevin learned to control his new absorbing powers in the Null Void (Confirmed by Dwayne McDuffie). It is revealed in the episode All That Glitters that the transmutation actually serves as a second skin/coating that eventually peels away as he takes damage. In the episode Plumbers' Helpers, Kevin can absorb multiple materials at once, as demonstrated by absorbing both nickel, copper and zinc(from loose change in his pocket). Dwayne McDuffie stated that Kevin can, in fact, still absorb energy, but is "afraid to", a plausible reason, considering his previous mutation. He requires a decent amount of material to completely encase himself. This ability has once been used productively when Kevin was forced to synthesize a coating of a living gem known as Taedinite, thus incapacitating him, Vulkanus mentioned that it's the rarest gem in the galaxy with the amount he chipped off from Kevin he was able to buy a perment to "renovate" the earth and Paradox mentioned that with the amount Vulkanus chipped off Kevin is the largest amount in the galaxy.

In the Alien Force season 3 premiere, Kevin loses the ability to revert to his human form after a feedback blast, caused when Ben tampers with the Omnitrix, imprints various materials onto him, such as concrete, metal, wood, and what appears to be Diamondhead crystals or quite possibly Taedenite crystals from "Kevin's Big Score". In addition,Kevin;gains enhanced strength and durability and limited shape shifting abilities, seen when he shifts his hands into a variety of different tools, such as a mace and large clippers. In The Final Battle: Part 2 he was turned back to normal and got his old powers back after the Omnitrix self destructed.

Trivia

 * In the Ben 10: Alien Force season 2 finale "War Of The Worlds, Part 1", it is revealed that Kevin's middle name is Ethan, making his full name Kevin E. Levin, officially connecting the pun to his old nickname "Kevin Eleven". Ben finds this extremely hilarious, saying that he has lost "all remaining pretense of cool".
 * He is part alien. Even though his parents supposedly abandoned him (this may be a lie Kevin invented to impress Ben, because he doesn't answer to anybody) Kevin still has a mother as shown at the end of Darkstar Rising, when he tells Ben and Gwen that he will tell his mother about his new plumber's badge.
 * Kevin has been unable to transform back to his human form twice now. Both times were from tampering with the Omnitrix.
 * It is shown in Darkstar Rising that Kevin disliked the smoothie flavor that Ben had gotton him.
 * Like Ben, Kevin is a big fan of Sumo Slammer, as he is thrilled when Ben tells him there is going to be a Sumo Slammer Movie (in the episode Vengeance of Vilgax: Part 1), though later he calls it boring and acts as if he had never seen it.
 * In Trade-Off, Kevin is shown to have worn black briefs.
 * In Con of Rath, during a battle with Vulkanus he reveals he has dreams where he is confronted by his old enemies (or everyone he ever knew) and try to hurt him. He mistakenly assumes that everybody has dreams like that, only to discover he was mistaken when Gwen says, "I don't have dreams like that."
 * Despite his heroic actions in Alien Force, Kevin has been shown to occasionally engage questionable actives, from minor crimes like speeding, to helping his old partner Argit sell weapons to both sides of an alien war, (for a cut of the profits,) that Ben was trying to end in the episode Simple. This makes him sort of an anti-hero.
 * In Ben 10, Kevin told Ben that he was a mutant, which was how he gained his powers. This was probably because, at the time, Kevin didn't know/believe aliens were real or that his father was one.
 * Strangely, Kevin's hometown is Bellwood also, same as Ben's.