Karen M. McManus is an American author of young adult fiction. She is most known for her first novel, One of Us Is Lying, which spent more than five years on the New York Times bestseller list.It received a starred review from Publishers Weekly. "One of Us Is Lying" was optioned as a pilot by NBC and the television adaption premiered on Peacock in October 2021. Its sequel, "One of Us Is Next", received a starred review from Publishers Weekly. For Two Can Keep a Secret, which was McManus’ first standalone novel outside of the One of Us Is Lying trilogy, Kirkus Reviews gave it a starred review and named it one of the best books of 2019.