http://www.kryptonsite.com/

According to Krypton Site, Marc McClure – who some may also remember as Marty’s brother in the “Back to the Future” movies – will appear in an episode in January. The same episode sees the return of the evil Brainiac (played by James Marsters).


Marc McClure, the Jimmy from the “Superman” movies from the 1970's is set to appear on Smallville.

That makes at least six guest stars on SMALLVILLE who have had some
kind of Superman connection: Christopher Reeve, Margot Kidder, Marc
McClure, Terence Stamp (voice), Helen Slater, and Dean Cain. Did I leave
out anyone? (Well, besides Lynda Carter, who was TV's Wonder Woman)