Superman: American Alien #7 - Without a doubt, Superman: America Alien is the best Superman comic DC has published since Grant Morrison and Frank Quitely's All-Star Superman. We only wish it didn't have to end. This final chapter moves a little it further in Superman's career. Now firmly established as Metropolis' defender, Superman has his first encounter with a super-powered villain from another world.
Joe Shuster's iconic Action Comics #1 from 1938. This cover has been burned into culture and marked the beginning of the Golden Age of comics. I couldn't picture Superman without seeing this image or Christopher Reeve catching Margo Kidder.