José Carlos Fulgencio Pedro Regalado de la Riva-Agüero y Looz Corswarem (Brussels, Belgium, 25 May 1827 – Lima, Peru, 16 August 1881) was a Peruvian politician and diplomat.

He was the son of José de la Riva Agüero, Marquess of Montealegre de Aulestia, first President of Peru, and the Belgian princess Caroline-Arnoldine de Looz-Corswarem.

In 1858, Riva-Agüero was elected Alternate Deputy of the Congress for Huarochirí and Deputy of the Constituent Congress two years after.

Member of the Civilista Party, was Minister of Finance in 1872,[1] Minister of Foreign Affairs and member of the Senate of Peru.

He served as Ambassador to Belgium, as well as to France.