Peter Lerangis (b. 1955) is a bestselling author of middle-grade and young-adult fiction whose novels have sold more than four million copies worldwide. Born in Brooklyn, New York, Lerangis was working in musical theater when he began editing fiction, which eventually led to writing novels of his own. He got his start writing novelizations under the pen name A. L. Singer, as well as installments of long-running series such as the Hardy Boysand the Baby-sitters Club. Lerangis began publishing under his own name with 1994's The Yearbook and Driver's Dead.

In 1998 Lerangis introduced Watchers, a six-novel sci-fi series that won Children's Choice and Quick Picks for Reluctant Readers awards and led to an invitation to dine with the President of Russia at the White House. His other work includes the Abracadabra novels; the Spy X series; Drama Club, a four-book series about high-school theater based on his own Broadway experiences; and exactly three and a quarter books in the New York Times-bestselling 39 Clues series. He lives with his family in New York City, not far from Central Park.