Kevin 11 (Ben 10)

The supervillain alter-ego of Kevin Levin, Ben's original Evil Counterpart and second major nemesis. An 11-year-old boy Ben befriends in New York City, Kevin seems like your average street kid delinquent, but actually has superpowers that allow him to absorb energy. After revealing himself to be a disturbed sociopath, Kevin absorbs the power of Ben's Omnitrix, which backfires on him when it eventually mutates him into a hideous amalgamation of all 10 of Ben's aliens. Now dubbing himself "Kevin 11", he is obsessed with getting Revenge on Ben.