Ralph Drew Flanagan (December 14, 1918 – February 8, 1988) was an American competition swimmer who represented the United States at two consecutive Summer Olympics during the 1930s. As a 13-year-old at the 1932 Summer Olympics in Los Angeles, California, Flanagan competed in the semifinals of the men's 1,500-meter freestyle. Four years later at the 1936 Summer Olympics in Berlin, Germany, he won a silver medal as a member of the second-place U.S. team in the men's 4×200-meter freestyle relay. Individually, he finished fourth in the men's 400-meter freestyle and fifth in the men's 1,500-meter freestyle.