'The Walking Dead' season 6 spoilers: Here's why Steven Yeun worried about Glenn

Threats from external sources will escalate in season 6 of AMC's "The Walking Dead", which will be premiered on 11 October.

Andrew Lincoln's Rick Grimes and company is just about settling down in Alexandria Safe-Zone, and the first episode of the upcoming season will see them being attacked by quite a number of zombies.

"We are unashamedly a zombie show, and we will give you more zombies than you have ever seen before," Lincoln told NYDaily News. "I know I say this every year, but I think this time we've maxed out on what we're capable of doing. It's the biggest, most ambitious season yet, and the crew have brutalised themselves to get this made."

As fans of "The Walking Dead" comic book series by Robert Kirkman have a vague idea on what to expect when the series returns, many are convinced that actor Steven Yeun won't be hanging around for long.

In the books, Yeun's character Glenn dies shortly after Negan, one of the most notorious comic book villains, is introduced. In the book, Negan, the leader of another group of survivors called the Saviors, uses his baseball bat to beat Glenn to death. The AMC show is catching up to the book, and recent casting call hints at Negan's appearance before season 6 ends.

Understandably, Yeun is worried.

"Yes, I'm worried about Glenn," Yeun told the media outlet. "But we're still in the middle of filming. There's still a lot of story to tell, and a lot of different stories to tell from the graphic novels."

As for what else to expect in the season premiere, Lincoln said the first half of the season is the consequence of what happens in the final moments of season 6 episode 1 entitled "First Time Again."

"A bow is being pulled back, and in the last 30 seconds of the premiere, that bow is released, the arrow flies, and the next eight episodes are about the fallout from what happened in those last 30 seconds," Lincoln said.