Ralph R. Hepburn (April 11, 1896 – May 16, 1948) was a pioneer American motorcycle racing champion and an Indianapolis 500 racecar driver. Born in Somerville, Massachusetts, Hepburn's family moved to Los Angeles, California when he was ten years old. He began riding motorcycles as a teen and his skills led to him signing on with a cycle performing group in 1914 that toured the West Coast and parts of the American Midwest. He then began competing in on board tracks, then on dirt. His racing career was interrupted during 1917 and 1918 due to World War I.