"Both parties acknowledge that there is a difference of opinion about where the show should go moving forward, and conclude that it is best to part ways," AMC and Mazzara said in a joint statement. "This decision is amicable and Glen will remain on for post-production on season 3B as showrunner and executive producer."
Mazzara also issued his own statement following the announcement.
"My time as showrunner on The Walking Dead has been an amazing experience, but after I finish season 3, it's time to move on," he said. "I have told the stories I wanted to tell and connected with our fans on a level that I never imagined. It doesn't get much better than that. Thank you to everyone who has been a part of this journey."
Robert Kirkman, an executive producer and the creator of the comic book series upon which the show is based, said he was "in full support" of the decision. Fellow executive producer Gale Anne Hurd added that she is "appreciative and grateful to Glen for his hard work" and she knows "the series is in great hands with one of the most talented and dedicated casts and crews in the business."
Mazzara replaced original showrunner Frank Darabont in 2011, when he and AMC also parted ways during the production of Season 2. In its most recent season, The Walking Dead has been achieving unheard-of ratings for cable programming. Season 3 has averaged roughly 10.1 million viewers per week, topping all broadcast shows in its timeslot. And for its midseason finale, the show went out on a (very) high note, attracting attracted 10.5 million viewers, and a whopping 6.5 million viewers in the adults-18-to-49 demographic. That's a 58 percent increase and 54 percent increase, respectively, over the Season 2 midseason finale last year.
"Last year we were criticized for taking our time and having a slow pace," Mazzara told TVGuide.com in November. "This year, we've accelerated it, and I have heard some feedback that we're blowing through story. Everybody seems to have an opinion on how fast or how slow The Walking Dead should go. As a showrunner, I just have to go with, 'What are the best stories? And what feels real?'"
There's no word on who will replace Mazzara.
Are you happy about the renewal? Do you think Mazzara's exit will impact the show in the future?
Additional reporting by Natalie Abrams.