A fan theory has been going around lately that Breaking Bad is actually a prequel to The Walking Dead. People have noticed some crossover themes in the shows, which isn't all that surprising, since they are produced by and for the same channel. But what if Heisenberg's drugs somehow caused the zombie apocalypse? Netflix explains this theory.
Someone connected the dots that led from one show to the other. You know, the dots that really aren't there. Robert Kirkman wrote the comic book The Walking Dead, while Vince Gilligan came up with the idea for Breaking Bad during the writer's strike a few years back. Kirkman has stated that he will never explain what caused the zombie apocalypse in The Walking Dead. Therefore, it's up to the fans to figure it out. This idea is as good as any! -via Laughing Squid