Mark T. Sullivan

Mark T. Sullivan is an American novelist who became one of James Patterson's collaborators on the Private series, co-writing several installments including entries set in Los Angeles and other locations within the Private International franchise founded by protagonist Jack Morgan. Before his Patterson partnership, Sullivan built a career as an investigative journalist and independent thriller writer, with novels drawing on his reporting background in fields such as environmental crime and international intrigue. Sullivan's solo work includes acclaimed historical fiction, notably Beneath a Scarlet Sky, a bestselling World War II novel based on the true story of an Italian teenager who became a resistance spy, which brought him significant critical and commercial attention beyond his earlier thriller output. His journalism background gave his Private novels a grounded, research-driven texture consistent with the franchise's globe-spanning, high-stakes plotting. Sullivan continues to write across both collaborative commercial thrillers and his own historical and literary fiction, and is recognized for successfully bridging the fast-paced Patterson brand with more deeply researched standalone work.