Rennie Airth (born 1935) is a South African novelist who currently resides in Italy. Airth has also worked as foreign correspondent for the Reuters news service.
His works include Snatch! (1969), Once A Spy (1981), and a trilogy of murder mysteries set in England between 1921 and 1944 featuring Detective Inspector John Madden of Scotland Yard. The first of these, River of Darkness (1999), won the Grand Prix de Littérature Policière for best international crime novel in 2000 and was nominated for Edgar, Anthony, and Macavity awards. Airth found inspiration for the book in a scrapbook about his uncle, a soldier killed in World War I. A sequel, The Blood-Dimmed Tide, was published in 2003, and the third book, The Dead of Winter, in 2009.