John Robertson Quinn (July 17, 1889 – April 29, 1979) was an American politician who served as the sixth national commander of the American Legion from 1923 to 1924. He also served on the Los Angeles County Board of Supervisors from 1930 until 1936 and as Los Angeles County Assessor from 1938 to 1962.

John Robertson Quinn was born in Porterville, California, where he grew up and attended local schools. He was a member of The American Legion who served as the sixth national commander from 1923 to 1924.^[1] A successful rancher, Quinn was an active participant in the business community in Tulare and, for a time, its Ku Klux Klan. While he left in late 1922, for a time he viewed the organization as standing for "the highest ideas of Americanism.^[2] He was a primary candidate for mayor of Los Angeles in 1929.^[1] He was appointed by Governor C. C. Young on May 12, 1930, to replace Reuben F. McClellan on the Los Angeles County Board of Supervisors. He served until 1936, when he was replaced by Leland M. Ford. He died on April 29, 1979, at the age of 89.^[3]