Dorothy Prior was a Canadian competitive swimmer who specialised in the breaststroke. Prior first competed in the 1920s, winning multiple races in her youth. In 1928 she set a Canadian record in the 220 yards breaststroke by beating her own personal best time by nearly 20 seconds. That same year she broke the American record in the event at the US Championships, becoming the first Canadian swimmer to break an American record in swimming. These performances earned Prior, who was only 16-years-old at the time, a place on the Canadian Olympic team for the 1928 Amsterdam Games. Despite her good performances before arriving in Europe, she was eliminated in the heats of the 200 metres breaststroke. The following year she bettered several of her swimming records and won the Gale Trophy in a five-event competition to determine the best swimmer in Canada. Prior continued to win races, which earned her another appearance at the Olympics, this time at the 1932 Los Angeles Games.