Peter Duncan Lerangis is an American author born on August 19, 1955, in Brooklyn, New York. He is best known for his children's and young adult fiction, particularly the Seven Wonders series and his work on The 39 Clues series.

Lerangis's diverse portfolio includes titles such as The Viper's Nest and The Sword Thief, which are part of The 39 Clues series, as well as the historical novel Smiler's Bones and the YA dark comedy-adventure novel WTF. His other series include Drama Club, Spy X, Watchers, Abracadabra, and the Antarctica two-book adventure.

He has also been a prolific ghostwriter for well-known series such as Three Investigators, Hardy Boys Casefiles, Sweet Valley Twins, and more than forty books in The Baby-sitters Club series and its spin-offs.

In addition, Lerangis has authored novels based on screenplays, including The Sixth Sense, Sleepy Hollow, and Beauty and the Beast, as well as five video game novelizations in the Worlds of Power series created by Seth Godin.