I'll agree that Watchmen had a great influence on the superhero genre. Have you had a chance to check out Invincible, written by Robert Kirkman and published by Image? Not a graphic novel, but an ongoing comic that is at its core, a different take on the Superman type of hero. Then there's also Powers which has become Powers Bureau written by Brian Michael Bendis and drawn by Michael Avon Oeming (who has his own excellent series, The Mice Templar) . Which is kind of like X-Files set in a universe where people have . . . well, super powers. I hear Powers is slated to become a TV series. I'm a little surprised that the works of Moebius or Jodorowsky haven't been mentioned. Perhaps their influence is not as well known, but I certainly think that their work has gone a long way to advance comics and graphic novels as a genre.