Superman III (1983, Annette O'Toole, Christopher Reeve, Jackie Cooper, Richard Pryor, Robert Vaughn)

Superman matches wits with an evil mastermind and a computer genius who discovers the one substance that can harm the Man of Steel. Combining the known ingredients of Kryptonite with a guess at the unknown, the genius invents a new Kryptonite that doesn't kill Superman--it turns him evil. Meanwhile, a giant computer has been built for the mastermind that becomes self-aware and cannot be shut off.