Margaret Petherbridge Farrar (March 23, 1897 – June 11, 1984) was an American journalist and the first crossword puzzle editor for The New York Times, from 1942 to 1968. Stanley Newman has referred to her as a "crossword genius", and credits her with the creation of "many, if not most" of the rules that guide modern crossword design.
Her career in crossword puzzles began at the New York World in 1920; although she had been hired as the publisher's secretary, she was told to assist crossword inventor Arthur Wynne in proofreading puzzles prior to publication. Her puzzles soon became more popular than Wynne's.
In 1924, she was hired by Richard L. Simon and Max Schuster as one of the three creators of the first crossword puzzle book; the book's success launched Simon & Schuster as a major publisher, and at the time of Farrar's death in 1984, she was working on the 134th volume in the series.
A lifelong resident of New York City, she attended Berkeley Institute in Brooklyn and graduated from Smith College in 1919.
In 1926, she married John C. Farrar, one of the co-founders of Farrar & Rinehart and Farrar, Straus and Giroux.