Frank Putnam Day (August 15, 1884 - June 15, 1912) was an employee of the Locomobile Company of Bridgeport, Connecticut.
Day was born on August 15, 1884 in Hartford, Connecticut, as the son of George Herbert Day, Sr. and Katherine Beach. He was educated in the Hartford schools, dropping his education before finishing high school, to take up work. For a time, he was employed with the Hartford Rubber Works Company, but in 1906, he entered the employ of the Locomobile Company of Bridgeport, Connecticut. He lived in Bridgeport for five years until October 1911, when he removed to Atlanta, Georgia, to manage the company's branch in that city.
On June 15, 1912, Day died in Atlanta, Georgia, from typhoid fever.
Day married Marjorie Munsill in 1908. The couple had no children.