A half-century after its release, Rosemary’s Baby remains one of the scariest films of all time, yet star Mia Farrow’s most shocking moment during production had nothing to do with playing the mother of Satan’s child. “Frank’s lawyer entered the set, carrying a brown envelope containing divorce papers,” she recalls of being served by husband Frank Sinatra, who wanted her to drop out of Roman Polanski’s thriller to co-star with him in a lesser 1968 film, The Detective. “This was the first mention of divorce. I held myself together to sign on the spot all the papers without reading them.”

Mia may have maintained her sense of calm, but filmgoers lost theirs when the adaptation of Ira Levin’s bestseller packed theaters. “Rosemary’s Baby was a huge hit, and it started a big move for modern horror,” says film critic Stephen Whitty, who recently spoke at a screening of the 50-year-old film. “It’s a story about Satanism, but it’s set in the Dakota — that nice Manhattan apartment building — with recognizable characters. It’s not a story about vampires or werewolves.”

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The role of Rosemary made Mia, then best-known for TV’s Peyton Place, a major movie star, but she wasn’t Polanski’s first choice. He considered Jane Fonda (who opted to make husband Roger Vadim’s Barbarella instead) and his real-life wife Sharon Tate, who was brutally slain by the Manson family a year later. “This is one of the most difficult woman’s parts I can imagine,” the director said. “I had only seen Mia on the cover of Life.”

Yet Mia won him over, and they threw themselves into filming with reckless abandon. For one scene in which a dazed Rosemary wanders into traffic, “Roman and I marched right in front of the oncoming cars,” Mia remembers, with the filmmaker pointing to her padded stomach and reassuring her, ‘Nobody will hit a pregnant woman.’” The movie put the French-Polish director on Hollywood’s map and made a household name of Ruth Gordon, a 72-year-old screenwriter who won an Oscar as Rosemary’s pesky neighbor. “The first film that I was ever in was in 1915,” she said. “I feel absolutely groovy.”

rosemary's baby getty images

Rosemary’s Baby even set fashion trends, as women copied Mia’s stylish pixie ’do. “I had cut it myself earlier that year — with a pair of fingernail scissors,” Mia says. Despite rumors the coif caused a marital rift, Frank “loved the cut, and so I kept it short.” The film’s influence on the modern pop-cultural landscape has lasted even longer. “I don’t think you would’ve seen Stephen King, The Exorcist, The Omen or any of those other movies about the Antichrist without Rosemary’s Baby,” says Whitty. “It definitely has a legacy — and staying power.”