All Things Walking Dead

Here's a video that looks ahead to season four of The Walking Dead.
The show is reportedly casting a new regular character named Roy Stark, who is described as "a former army medic who is deeply haunted by his past -- pre- and post-zombie apocalypse... [and] as a result, he's a bit of a loner, although he maintains a charming/self-deprecating/confident public face. [TV Line]
Comics creator Robert Kirkman previews the fourth season, starting with the return of David Morrissey's Governor:

Yeah, he’s still very much in the mix. That’s certainly not the last that we’ll see of him. When we see him again and where we see him again, that’s the big question. It’s not going to be like it was in Season 3; it’s not going to be Rick and the Governor on a collision course with a conflict between them. He’ll be used in very different ways next season.
Carl and Rick seemed to have almost switched roles to some degree, with Carl being incredibly cold and Rick finding a sense of optimism to some degree. How does that inform their relationship from this point forward?

Rick has had a success. The people at the prison have survived this conflict with the Governor, he brought people from Woodbury into the prison, and he’s kind of had this big win. He’s had this moment where he’s brought people together and he’s doing good things. But he’s had this tremendous loss in that Carl has lost this piece of his humanity. This has been Rick’s main mission throughout the show, to protect his family. We’ve seen two very big failures on that front this season. Moving into next season, we’re going to see a very different Rick, but one of his main goals is to manage this situation with Carl and see if he can bring him back from this darkness that’s crept into him. Whether or not he’s able to do that, we’ll have to see. But this is a big change in the character of Carl, but it’s something that’s going to be weighing heavily on Rick next season.

Kirkman offers this general teaser for the upcoming season:

I’ll say that there are a lot of familiar elements that are remaining. Michonne is still around, Rick and his group are still in the prison, the Governor’s still out there… so there are a lot of things that are carrying over from Season 3 to Season 4, but I can’t stress how different things are going to be. There are going to be some radical changes to those elements that are going to bring in a lot of new storytelling. While [Season 4] does seem somewhat familiar, it’s going to be vastly different from Season 3.