Sylvia June Day is an American writer who grew up in Orange County, California. She also writes under the pseudonyms S. J. Day and Livia Dare. Her novels span the romance and fantasy genres. Her work has appeared on multiple bestsellers lists, including the New York Times, USA Today, Publishers Weekly, the Wall Street Journal, and the Washington Post. She is the author of the popular Renegade Angels Series and the Crossfire Series.