Margaret Peterson Haddix (born April 9, 1964) is an American writer known best for the two children's series, Shadow Children (1998–2006) and The Missing (2008-2015). She also wrote the tenth volume in The 39 Clues, published by Scholastic.


She wrote her first book in 6th grade, "I thought it was amazing" she said, "but I realized it was only 20 pages long." She graduated from Miami University in Oxford, Ohio with degrees in English/journalism, English/creative writing, and history. Before her first book was published, she worked as an actor with Fort Wayne, , a newspaper reporter in Indianapolis, and a community college instructor and freelance writer in Danville, Illinois.

Haddix has written more than 30 books for children and teenagers. including 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, Uprising, Palace of Mirrors, Claim to Fame, The Always War, Game Changer, the Shadow Children series, and the Missing series. She also wrote Into the Gauntlet, book 10 in the 39 Clues series. Her books have made New York Times Best Seller lists and American Library Association (ALA) annual book lists. and they have won the International Reading Association's Children's Book Award and more than a dozen state reader's choice awards. Mrs. Haddix has stated on September 13th 2016, at a middle school in Dayton, Ohio, that she as no favorite book of hers, and that she used to think she would never write a series.


Haddix has received the International Reading Association Children's Book Award, Champions league ,some ALA listings on Best Books for Young Adults and Quick Picks for Reluctant Young Adult Readers, The National Kids Award, and readers' choice lists in more than 29 states.