Metallo

John Corben, the Kryptonite-powered cyborg revived for the specific task of eliminating Superman, after an accident he was given a cybernetic body by a crazy scientist who believed that Superman was a scout sent to survey Earth for a Kryptonian invasion and later upgraded by Lex Luthor to accomplish this task.
After so many battles with the man of steel, it became obvious that just the peace of Kryptonite wasn't enough since each time he was close to victory a third party intervened.
He needed to be smarter about this, figure out something more than just exposing him to the usual green light of his power source.