Last week, we invited readers to share their theories about how "Breaking Bad" will end. The online responses—more than 300 and counting—show how closely fans have been relishing every detail of the story. Most predictions involve specific plot devices (especially a certain firearm). As for the fate of the show's antihero, Walter White, a surprising number of fans expect him to die by his own hand—but not before wiping out the criminal gang many call "the Nazis."

We also asked readers how they would end...