Jack Chapman Medica (October 5, 1914 - April 15, 1985) was an American competition swimmer, Olympic champion, and former world record-holder in two events.
At the 1936 Summer Olympics in Berlin, Germany, Medica won a gold medal in the 400-meter freestyle and set a new Olympic record at 4:44.5, becoming the only American swimmer to win a gold medal at the Berlin Olympics. He received a silver medal for his second-place performance in the 1,500-meter freestyle, recording a final time of 19:34.0. Medica also received a second silver medal as a member of the runner-up U.S. team in the men's 4200-meter freestyle relay, together with American teammates Ralph Flanagan, John Macionis and Paul Wolf. The American relay team finished with a time of 9:03.0, behind the winning Japanese team.