They come for anime and original comic-book art. They come for video games, collectible figurines and to show off their “Star Wars” or “Lord of the Rings” costumes. They might even come to buy a winged helmet or a suit of armor. But many of the 120,000 fans who descend on Comic-Con, the nation’s largest pop-culture convention, come for a glimpse of Hollywood’s latest offerings and biggest stars. Sandy Cohen reports.