Jon Alexander "Jack" Douglas (September 10, 1936 – July 27, 2010) was a professional American tennis player and college football quarterback.
Douglas was born in Hot Springs, Arkansas, the only child of Dortha and Gordon Douglas. In 1944 he and his family moved to Santa Monica, California. He graduated from Santa Monica High School, where he played football, tennis, and basketball.
He attended Stanford University, where he was Stanford's first All-American in tennis in 1957, and earned the honor again in 1958, when he was runner-up in both singles and doubles competition at the NCAA Men's Tennis Championship.
Douglas was also a quarterback on Stanford's football team. He played backup to John Brodie for two years, and when Brodie graduated, became the starter for the 1957 season, leading the team to a 6–4 record.
After graduating from Stanford, Douglas entered top-level competitive amateur tennis. From 1960 to 1962, he was in the top ten of U.S. players, with his best finish coming as a quarterfinalist in the 1961 U.S. Open.
Following his service in the U.S. Marine Corps Douglas played on the U.S. Davis Cup team in 1961 and 1962, scoring the only point for the U.S. as they lost the 1961 Davis Cup finals to host country Italy.
Following his tennis career, Douglas founded a successful eponymous real estate company in Southern California. He was inducted into the Intercollegiate Tennis Association Hall of Fame in 1996, and is a member of the Stanford Athletic Hall of Fame. In 1995, the Jon Douglas Company merged with Prudential to form the Prudential Jon Douglas Company and was acquired by Coldwell Banker in September 1997.