Margaret Peterson Haddix, born on April 9, 1964, is a distinguished American author best known for her contributions to children's literature, notably through the acclaimed series Shadow Children (1998–2006) and The Missing (2008–2015). She also made a significant mark by writing the tenth volume in the collaborative series The 39 Clues.

Having grown up on a farm near Washington Court House, Ohio, Haddix's early life was steeped in the rural landscapes that would later influence her storytelling. She pursued higher education at Miami University in Ohio, where she earned degrees in English/journalism, English/creative writing, and history. Before achieving literary fame, Haddix honed her skills in the real world through various roles, including 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 prolific career, Haddix has penned more than 25 books for children and teens. 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, Dexter the Tough, and Up.