SAN DIEGO - The world's largest fan convention bid a poignant farewell to the star of the most successful show in cable TV history on Saturday as zombies took over San Diego Comic-Con.

An extensive line-up of stars descended on the city's sprawling convention center to whet appetites for AMC's "The Walking Dead" and its sister show "Fear the Walking Dead."

The departure of British actor Andrew Lincoln, who has appeared as Sheriff Rick Grimes in almost every episode since the 2010 pilot, has been an open secret since May, confirmed inadvertently by executive producer Robert Kirkman.

But the official announcement was reserved for Comic-Con, an annual pop culture celebration that attracts more than 100,000 devotees to southern California, many in elaborate costumes, every July.

"There seems to be an elephant in the room. This will be my last season playing the part of Rick Grimes," Lincoln, 44, told the packed 6,500-seat Hall H, prompting a dismayed murmur that spread throughout the arena.

Based on a comic book of the same name by a trio of writers including one of the show's executive producers Robert Kirkman, the post-apocalyptic zombie-ridden vision of the United States portrayed in "The Walking Dead" has proved uniquely resonant.

Dwarfing competition like HBO's "Game of Thrones" in the US, it has the highest total viewership in cable history and, crucially, the highest audience of 18-49s for any kind of US television between 2013 and 2017.

The show centers on Lincoln's Grimes, who wakes up in a hospital bed after getting shot, only to find he is alone in a world of vicious, flesh-eating reanimated corpses - known as "walkers" on the show.

"I got kind of choked up. It's been nine years of coming here," Lincoln told reporters after what will be his last sojourn to San Diego on behalf of "The Walking Dead."

"I love this place and I love seeing the fans, and you've been such a vital part of this experience. But my relationship with Mr Grimes is far from over."

It was unclear if he was talking about the current shoot for his final episodes, the possibility of appearing in one of the franchise's numerous side projects, or something else entirely.

The ninth season, coming in October, takes place two years after the "All Out War" saga of the previous two, with story editor Angela Kang taking over from veteran showrunner Scott Gimple. - AFP