Wow, we didn't see this one coming. After weeks of the cast and crew of The Walking Dead teasing a mysterious new threat, Walking Dead creator Robert Kirkman has spoiled exactly what the new threat is. If you don't want to be spoiled, then stop reading now. In an interview with Robert Kirkman, TV Guide asked him about some of the new threats that fans will be seeing in Season 4. Instead of giving a vague hint like he has in the past, Kirkman just straight out told TV Guide what the new threat is. Kirkman said, "Mother Nature is rearing it's ugly head at a time when we're completely incapable of combating it. This new threat is this Spanish flu-type sickness that is ravaging these people. That's really wrecking things for them. Aside from having The Governor (David Morrissey) looming on the horizon or any other kind of human threat that is out there, or zombies — which is something they're always fighting — they've also got to deal with this thing, which is possibly more deadly than anything they've faced yet." Showrunner Scott Gimple also answered the question, but he doesn't drop a spoiler like Kirkman. Gimple said, "As far within the prison, there's a threat that doesn't come from the outside world, it comes from within the prison. We have a whole panel of threats this season. A virtual smorgasbord of threats." So even though Kirkman has spoiled one of the mysterious new threats as being a version of the flu, it sounds like Rick and his group will be facing several new threats in Season 4.