Antoine-Florent Guillain (7 February 1844 – 19 April 1915) was a French maritime engineer who designed a major upgrade to the port of Dunkirk, and rose to a senior level in the Ministry of Public Works.He was elected to the chamber of deputies in 1896 as a moderate Progressive Republican, and was Minister of the Colonies in 1898–99.He was appointed president or director of several major mining, shipbuilding, steel making and railway enterprises, and was a director of the Suez Canal Company and the Banque de France.