O'Callaghan, Maxine: Author of the Delilah West private eye series and the Dr. Anne Menlo suspense series.
O'Kane, Leslie: Author of both the Molly Masters and Allie Babcock series. Synopses, biography, and cartoon gallery are available.
O'Neil DeNoux: Site for crime-fiction author O'Neil DeNoux.
O'Shaughnessy, Perri: Author(s) of the Nina Reilly legal mysteries.
Olsen, Eric B.: Official web site for mystery author Eric B. Olsen and his Steve Raymond, D.D.S. mystery series; read excerpts from his latest novel online
Olson, Karen E.: Information about the author of Sacred Cows, which features police reporter Annie Seymour.
Orrell, David: Author of Gaia, an eco-thriller set in Latin America. Includes a synopsis, excerpt, and information about the Gaia Theory.