John Cashmore was an American politician from New York City who served as borough president of Brooklyn from 1940 to 1961. He was the Democratic candidate for U.S. Senator from New York in 1952, losing to the incumbent Republican Irving McNeil Ives. He served as a member of the New York Democratic State Committee from 1938 to 1944 and was a delegate to the Democratic National Convention from New York in 1948, 1952, 1956 and 1960. Prior to entering politics, Cashmore was an aide to the general manager of the New York Edison Company and a furniture manufacturer.

Cashmore married Edythe Tenney. They had one son, James John Cashmore.