Margaret Peterson Haddix is an acclaimed American author, best known for her engaging children's series, Shadow Children (1998–2006) and The Missing (2008–2015). She also contributed to the renowned series, The 39 Clues, by writing its tenth volume.

Born on April 9, 1964, Haddix grew up on a farm near Washington Court House, Ohio. She pursued her education at Miami University in Ohio, obtaining degrees in English/journalism, English/creative writing, and history.

Before embarking on her successful writing career, Haddix gained experience as a newspaper copy editor in Fort Wayne, Indiana, a newspaper reporter in Indianapolis, and a community college instructor and freelance writer in Danville, Illinois.

Throughout her career, Haddix has penned over 25 books targeted towards children and young adults. Some of her notable works include Running Out of Time, Don’t You Dare Read This, Mrs. Dunphrey, Leaving Fishers, Just Ella, Turnabout, Takeoffs and Landings, The Girl with 500 Middle Names, Because of Anya, Escape from Memory, Say What?, The House on the Gulf, Double Identity, and Dexter the Tough.