French colonial administrator who explored the areas of the present Congo (Brazzaville), Central African Republic, and Chad and helped establish French rule in equatorial Africa.

A naval officer, Gentil led an expedition from the French Congo down the Chari (Shari) River to Lake Chad in 1895–97, establishing a French protectorate over the sultanate of Bagirmi. In 1900 he was made governor of the Shari region and was one of the leaders of the campaign against the Muslim leader Rābiḥ az-Zubayr, whose defeat he described in La Chute de l'empire de Rabah (1902; “The Fall of Rābiḥ's Empire”). From 1904 to 1908 Gentil served as governor of the French Congo.