Juan José Nieto Gil (24 June 1804 – 16 July 1866) was a Colombian politician, Army general and writer.

In 1861, during the Colombian Civil War, he fought on the side of the Liberal rebels against the Administration of President Mariano Ospina Rodríguez, and acting in rebellion proclaimed himself President of the Granadine Confederation in his right as the Presidential Designate, relinquishing power four months later to the Liberal leader, General Tomás Cipriano de Mosquera y Arboleda, who led a successful coup d'état against the Conservative Government in Bogotá.

On 8 May 1860, amid rising tensions between Conservative party politicians in power and the Liberal opposition on the question of federated state's rights and sovereignty, the caudillo and President of Cauca, General Tomás Cipriano de Mosquera y Arboleda, broke relations with the central government and declared civil war against the Administration of President Mariano Ospina Rodríguez.

[1] Born 24 June 1804 in the settlement of Cibarco, between the towns of Baranoa and Tubará, in the Province of Santa Marta part of the then Viceroyalty of the New Granada.

Born to a humble family of scarce resources, his parents were Tomás Nicolás Nieto and Benedicta Gil, a mason and candlemaker respectively, who lived in the town of Baranoa and moved to Cartagena de Indias in 1811 following the Declaration of Independence of Cartagena Province as part of the larger struggle of the South American Wars of Independence that started in 1810 and gave birth to the Republic of Colombia.