Juan Gregorio Lemos (1764-1822) was an Argentine military man and politician who served in the Army of the Andes under the command of General San Martín.

[2] Lemos was born on May 24, 1764, in Mendoza, Argentina and was baptized on July 16 of the same year in the parish San Nicolás de Tolentino.

[6] In 1810, he requested the discharge of the army to occupy the position of Regidor of the city Council of Mendoza and then designated as Customs Administrator of that province until 1815.

[7] In 1816, Lemos was designated as Comisario de Guerra (Commissar of War) and Intendant General of the Army of the Andes.

[9] In 1820, Lemos accompanied General San Martín in his expedition to Peru, participating in the Declaration of Independence of that country on July 28, 1821.