Joaquín Demetrio Casasús (Frontera, Tabasco, 23 December 1858 – New York, United States, 25 February 1916), was a Mexican Economist, Jurist, politician, Diplomat and Writer.
He was a member of the Academia Mexicana de la Lengua, the correspondent academy in Mexico of the Real Academia de la Lengua Española, since 1904.
He was the director of the Academy from 1912 until his death in 1916.
He was also the Mexican Ambassador to the United States around 1910.