Mark Cox (born 5 July 1943) is a former tennis player from England, who played professional and amateur tennis in the 1960s, 1970s and 1980s. He was ranked as high as World No. 13 on the ATP rankings (achieving that ranking in August 1977). Cox was educated at Wyggeston Boys' School in Leicester and Millfield School in Somerset.

Cox obtained an economics undergraduate degree from the University of Cambridge (Downing College), where he was a member of the Cambridge University Lawn Tennis Club.

During his career, he won eight singles titles and three doubles titles, reached the quarterfinals at the US Nationals (in 1966), and the final at the event in Cincinnati (in 1977). He also played on Great Britain's Davis Cup team, and was on the team that reached the 1978 final against the United States. He has also gone down in tennis history as the first amateur player to beat a professional. In May 1968, at the British Hard Court Championships at Bournemouth, he beat the American Pancho Gonzales in five sets in two and a quarter hours. Cox also achieved big upset wins over No. 1 seed, Rod Laver, at the 1971 Australian Open, and over No. 2 seed, Ken Rosewall, at the 1972 US Open. Cox retired from playing in 1981. During his latter playing years and after his retirement, Cox has worked as a coach, and also as a television commentator for the BBC. He is also a Patron of a charity "CRY" (Cardiac Risk in the Young) and an Ambassador for the Win Tennis Academy at Bisham. He lives with his wife Susie in London.