George A. Romero, famed horror director who invented the modern zombie movie with 1968’s “Night of the Living Dead,” died Sunday at age 77, according to a statement from his manager, Chris Roe.

According to the statement, Romero died after a brief battle with lung cancer, with his wife, Suzanne, and his daughter, Tina, at his side. He passed away while listening to music from his favorite film, John Ford’s “The Quiet Man.”

Romero is best known for starting the modern zombie subgenre in horror movies with “Night of the Living Dead.” Released in 1968, the film helped push the boundaries of violence that could be depicted on film.

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Born in the Bronx to a Cuban father and a Lithuanian mother, Romero got his start as a filmmaker with commercial TV projects. One of those was a segment in 1960 for “Mister Rogers’ Neighborhood,” in which Mister Rogers teaches kids about how and why kids sometimes get their tonsils removed.

Eight years later, Romero went from educating kids to terrifying them with “Night of the Living Dead.” Produced on a budget of just $114,000, the film went on to gross a whopping $30 million at the box office. In 2017 money, that’s $211 million grossed against a budget of $802,000.

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The film was released just a few months before the implementation of the MPAA ratings system, meaning that even small children were able to buy tickets to the film.

When reviewing the movie upon its release, critic Roger Ebert recalled that the audience at the screening he attended mostly consisted of kids under the age of 16, all of whom quickly became terrified by what they had seen.

“The kids in the audience were stunned. There was almost complete silence,” Ebert wrote. “The movie had stopped being delightfully scary about halfway through, and had become unexpectedly terrifying. There was a little girl across the aisle from me, maybe nine years old, who was sitting very still in her seat and crying.”

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Today, “Night of the Living Dead” is widely considered to be not only a horror classic, but one of the best low-budget films ever made. It spawned a series of sequels that were written and directed by Romero, starting with 1978’s “Dawn of the Dead” and continuing with 1985’s “Day of the Dead,” 1990’s “Land of the Dead,” 2007’s “Diary of the Dead” and 2009’s “George A. Romero’s Survival of the Dead.”

“Dawn of the Dead” in particular is just as critically acclaimed as “Night of the Living Dead,” and just as successful. The film made $55 million ($206 million in 2017 dollars) on a budget of $500,000.

Upon reappraisal, critics have noticed social commentary laced into the “Dead” series, including racial conflicts in “Night” — the protagonist was played by African-American actor Duane Jones — and a satire of consumerism in “Dawn” since the film depicts survivors fighting zombies in a shopping mall.