Joaquín Demetrio Casasús (December 23, 1858 – February 25, 1916), a Mexican economist, lawyer, banker, politician, diplomat and writer who served on two occasions as Ambassador of Mexico to the United States.

[1] During the Porfiriato, he was a prominent member of the Cíentificos, a group of technocrat advisors to President Porfirio Díaz.

[2] In 1914, during the Mexican Revolution, his mansion in Paseo de la Reforma was occupied by the troops of General Lucio Blanco;[3] Casasús died in exile in New York City in 1916.

Along with fellow Federal Deputy, Manuel R. Uruchurtu, he managed to win the definite ruling of King Victor Emanuel II of Italy, in favor of Mexico and against the United States, thus establishing that the Río Bravo was Mexican and not part of the border.

During his life he wrote a great deal of books specially in topics of law and monetary economics and politics