Marc Jaffe was at a New Year’s Eve party in Hollywood in 1967 when a screenwriter named William Peter Blatty began chatting him up. Mr. Blatty said he had tried and failed to sell an idea for a novel — about a young girl possessed by a demon and the tortured priest who tries to save her. But Mr. Jaffe, editorial director of Bantam Books, the paperback publishing house in New York City, thought the idea had merit, and Mr. Jaffe gave him an advance of $26,000 to secure the rights to the novel, The Exorcist, which sold nearly a half-million copies and made the best-seller lists. What followed was the 1973 movie adaptation, which in turn boosted more paperback sales. By 1974, 10 million copies had been sold, making it, at the time, the second-best-selling paperback of all time, behind Mario Puzo’s The Godfather and ahead of Erich Segal’s Love Story.

An editor is lucky,” Mr. Jaffe told Clarence Petersen, author of The Bantam Story: Thirty Years of Paperback Publishing, “if he has one like that in his career.” As it happened, Mr. Jaffe had many, including Catcher in the Rye and Jaws.

Marc Jaffe, died on Dec. 31 at his home in Williamstown, MA. He was 102.