Ace Books is an American specialty publisher of science fiction and fantasy books. The company was founded in New York City in 1952 by Aaron A. Wyn and began as a genre publisher of mysteries and westerns. It soon branched out into other genres, publishing its first science fiction (sf) title in 1953. This was successful, and science fiction titles outnumbered both mysteries and westerns within a few years. Other genres also made an appearance, including nonfiction, gothic novels, media tie-in novelizations, and romances. Ace became known for the tête-bêche binding format used for many of its early books, although it did not originate the format. Most of the early titles were published in this "Ace Double" format, and Ace continued to issue books in varied genres, bound tête-bêche, until 1