John Albert Kramer (August 1, 1921 – September 12, 2009) was an American tennis player of the 1940s and 1950s, and a pioneer promoter who helped drive the sport towards professionalism at the elite level. Kramer also ushered in the serve-and-volley era in tennis, a playing style with which he won three Grand Slam tournaments (the U.S. Championships in 1946 and 1947, Wimbledon in 1947). He also led the U.S. Davis Cup tennis team to victory in the 1946 and 1947 Davis Cup finals.
Kramer won the U.S. Pro Championship at Forest Hills in 1948 and the Wembley Pro Championships in 1949. He won world professional championship 2-man tours in 1948 (against Bobby Riggs), 1949 51 (against Pancho Segura), and 1953 (against Frank Sedgman).
Kramer was ranked world no. 1 amateur player for 1946 by Pierre Gillou, Harry Hopman and Ned Potter. He was ranked world no. 1 amateur player for 1947 by John Olliff, Pierre Gillou and Ned Potter. In 1948 he was ranked the U.S. no. 1 professional in the USPLTA contemporary rankings for U.S. pro tennis play. Some recent tennis writers have considered Kramer to be the world no.