Metallo was set to be JJ Abrams "Superman: Flyby" villain, when he was set to direct the franchise reboot back in the early 2000's, before Bryan Singer signed on. Here's some concept art.
If they two will appear in "Superman: The Man Of Steel", who will play them? Could Warner bring Brian Austin Green and Michael Ironside back for the film? I'm thinking Green is a "YES" and Ironside could be a "NO".