John F. Hennessey (born October 27, 1900, Indianapolis, Indiana; died August 1981, Stuart, Florida) was a top American tennis player of the 1920s.

Hennessey was ranked among the 10 best American players three times, his highest ranking being No. 4 in 1928. In both 1927 and 1928 he was the World No. 8 ranked player. In 1925 he and Ray Casey reached the finals of the Wimbledon doubles. In an era in which tournament doubles matches were considered almost as important as singles, they lost one of the most famous matches in the early history of tennis, being beaten 4-6, 9-11, 6-4, 6-1, 3-6 by one of the great French teams of Jean Borotra and René Lacoste.

Hennessey and George Lott won the 1928 doubles title at the U.S. Nationals, the same year that Hennessey lost two singles matches in the final Challenge Round of the Davis Cup. Hennessey reached the quarterfinals of the 1927 U.S. National championship and the quarterfinals at Wimbledon in both 1925 and 1928. A July 14, 1924 Time Magazine article called him The Indianapolis Cyclone.

He also won the 1920 singles title in the tournament now known as the Cincinnati Masters. He reached the singles final there in 1919 and was the doubles champion there in 1917 (with Albrecht Kipp) and 1920 (with Fritz Bastian).

He won the doubles title at the Western Tennis Championships in 1926, and reached the singles final of the Western in 1921.

In 1927 at the Western Championships, he reached the finals in singles (defeating future International Tennis Hall of Fame enshrinee Wilmer Allison in the semifinals) and in doubles (with partner Emmett Pare).

Also in 1927, he was runner-up at the Illinois State championship, losing in a five-set final to Bill Tilden.

In 1984 Hennessey was one of the first four inductees into the USTA/Midwest Section Hall of Fame. There is an annual John F. Hennessey Open tournament in Indianapolis for junior players.