The author of Rosemary's Baby is Ira Levin. He was an American novelist, playwright, and songwriter. Levin wrote several best-selling novels, including Rosemary's Baby, The Stepford Wives, and Sliver. He also wrote the Broadway play No Time for Sergeants and the musicals Critic's Choice and Drat! The Cat!. Levin's works often featured horror, science fiction, and suspense elements. His novel Rosemary's Baby was adapted into a critically acclaimed film in 1968.