Len Duncan (July 25, 1911 Brooklyn, New York – August 1, 1998 Lansdale, Pennsylvania) was an American race car driver.

Duncan raced midget cars in seven decades from 1920s until the 1980s.

During World War II, received the honor of being assigned as President Harry S. Truman's driver during one of his visits to England.

[1] Mario Andretti credits Duncan with having a great influence on his professional life.

Duncan won eight American Racing Drivers Club (ARDC) championships during the thirteen years between 1955 and 1967.