Gary Hall Jr. is an American former Olympic swimmer. In his first Olympics at the age of 21 in Atlanta, Hall had only 6 years of swimming experience yet he already had a well-known rivalry with Russia's Alexander Popov. Hall and his teammates dominated the relay events, but Popov beat Hall and dominated in the individual events.

Hall represented the United States at the 1996, 2000, and 2004 Olympics and won ten Olympic medals five gold, three silvers, and two bronze. He is a former world record-holder in two relay events, including helping set the world record in both the 400 m freestyle and medley relays. Hall is well known for his personality. His "pro-wrestling like" antics before a competition include frequently strutting onto the pool deck in boxing shorts and robe, shadow boxing and flexing for the audience.

The Race Club is a swimming club founded by Hall and his father, Gary Hall Sr. The club was designed to serve as a training group for elite swimmers across the world in preparation for the 2000 Sydney Olympic Games. Hall Jr won a humanitarian award in 2004, at the Golden Goggle Awards.