George Romero, whose classic "Night of the Living Dead" and other horror films turned zombie movies into social commentaries and who saw his flesh-devouring undead spawn countless imitators, remakes and homages, has died. He was 77.

Romero died on Sunday following a battle with lung cancer, said his family in a statement provided by his manager Chris Roe. Romero's family said he died while listening to the score of "The Quiet Man," one of his favourite films, with his wife, Suzanne Desrocher, and daughter, Tina Romero, by his side.

Romero is credited with reinventing the movie zombie with his directorial debut, the 1968 cult classic, "Night of the Living Dead." The movie set the rules imitators lived by: Zombies move slowly, lust for human flesh, and can only be killed when shot in the head. If a zombie bites a human, the person dies and returns as a zombie.

Romero's zombies, however, were always more than mere cannibals. They were metaphors for conformity, racism, mall culture, militarism, class differences and other social ills.

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"The zombies, they could be anything," Romero told The Associated Press in 2008. "They could be an avalanche, they could be a hurricane. It's a disaster out there. The stories are about how people fail to respond in the proper way. They fail to address it. They keep trying to stick where they are, instead of recognising maybe this is too big for us to try to maintain. That's the part of it that I've always enjoyed."

"Night of the Living Dead," made for about $100,000, featured flesh-hungry ghouls trying to feast on humans holed up in a Pennsylvania house.

The movie was added by the Library of Congress in 1999 to its National Film Registry for works considered "culturally, historically, or aesthetically significant."

Romero's death was immediately felt across a wide spectrum of horror fans and filmmakers.

Sad to hear my favorite collaborator--and good old friend--George Romero has died. George, there will never be another like you. — Stephen King (@StephenKing) July 16, 2017

Romero has passed away. Hard to find words right now. The loss is so enormous. — Guillermo del Toro (@RealGDT) July 16, 2017

Romero's influence

Romero's influence could be seen across decades of American movies, from John Carpenter to Jordan Peele, the "Get Out" filmmaker. Many considered "Night of the Living Dead" to be a critique of racism in the United States. The sole black character survives the zombies, but he is fatally shot by rescuers. When Edgar Wright made 2004's "Shaun of the Dead," he acknowledged, "What we now think of as zombies are Romero zombies."

Ten years after "Night of the Living Dead," Romero made "Dawn of the Dead," where human survivors take refuge from the undead in a mall and then turn on each other as the zombies stumble around the shopping complex.

Film critic Roger Ebert called it "one of the best horror films ever made - and, as an inescapable result, one of the most horrifying. It is gruesome, sickening, disgusting, violent, brutal and appalling. It is also ... brilliantly crafted, funny, droll, and savagely merciless in its satiric view of the American consumer society."

Romero had a sometimes combative relationship with the genre he helped create. He called "The Walking Dead" a "soap opera" and said big-budget films like "World War Z" made modest zombie films impossible.

Romero maintained that he wouldn't make horror films if he couldn't fill them with political statements.

"People say, 'You're trapped in this genre. You're a horror guy.' I say, 'Wait a minute, I'm able to say exactly what I think,' " Romero told the AP. "I'm able to talk about, comment about, take snapshots of what's going on at the time. I don't feel trapped. I feel this is my way of being able to express myself."

The third in the Romero's zombie series, 1985's "Day of the Dead," was a critical and commercial failure. There wouldn't be another "Dead" film for two decades.

"Land of the Dead" in 2005 was the most star-packed of the bunch - the cast included Dennis Hopper, John Leguizamo, Asia Argento and Simon Baker. Two years later came "Diary of the Dead," another box-office failure.

There were other movies interspersed with the "Dead" films, including "The Crazies" (1973), "Martin" (1977), "Creepshow" (1982), "Monkey Shines" (1988) and "The Dark Half" (1993). There also was 1981's "Knightriders," Romero's take on the Arthurian legend featuring motorcycling jousters. Some were moderately successful, others box-office flops.

'That's not what I'm about'

George Andrew Romero was born on February 4, 1940, in New York City. He grew up in the Bronx, and he was a fan of horror comics and movies in the pre-VCR era.

His favourite film was Michael Powell and Emeric Pressburger's "The Tales of Hoffman," based on Jacques Offenbach's opera. It was, he once wrote, "the one movie that made me want to make movies".

Romero graduated from Carnegie Mellon University in Pittsburgh in 1960. He learned the movie business working on the sets of movies and "Mister Rogers' Neighborhood," which was shot in Pittsburgh.

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The city became Romero's home, and many of his films were set in western Pennsylvania. "Dawn of the Dead" was filmed in suburban Monroeville Mall, which has since become a popular destination for his fans.

Romero struggled to get films made late in life. The last film he directed was 2009's "Survival of the Dead," though other filmmakers continued the series with several sequels, including the recently shot "Day of the Dead."

But Romero held strong to his principles. A movie with zombies just running amok, with no social consciousness, held no appeal, he often said. "That's not what I'm about."