Frank Nelson Doubleday (January 8, 1862 – January 30, 1934), known to friends and family as “Effendi”, was a famous U.S. publisher. His most significant achievement was as founder of the eponymous Doubleday & McClure Company in 1897.

Frank Doubleday was a native of Brooklyn, New York, the son of a hatter. Early in life he became fascinated with the printing business and by the age of ten he had saved up enough money to buy his own printing press. He earned back his investment by printing advertising and news circulars for local businesses, and from that point never left the business. When Doubleday was 14, his father's business failed, and he was forced to leave school and find a full-time job. He went to work at the firm of Charles Scribner's Sons in Manhattan for the salary of $3 a week. Doubleday spent eighteen years at Scribner's, eventually rising to become the publisher of Scribner's Magazine and head of Scribner's subscription book department.

When Doubleday's relationship with J. Blair Scribner soured, he left the company and went into partnership with Samuel S. McClure, publisher of McClure's Magazine, to form the Doubleday & McClure Co. in March, 1897. The following year, Doubleday and McClure accepted a contract to manage the great publishing house of Harper & Brothers, at the instigation of their banker, J. Pierpont Morgan. On taking control, Doubleday dug thoroughly through Harper's books and decided that the company's finances were in a shambles, and Doubleday convinced McClure and Morgan to call off the deal. (Harper had gone heavily into debt in the Panic of 1893, and the extension of copyright to foreign authors in 1891 put a large dent in Harper's principal business, cheap domestic reprints of respected foreign authors.)