Juan de Mendoza y Luna, 3rd Marquess of Montesclaros (January, 1571 – October 9, 1628) was a Spanish nobleman, man of letters, and the tenth viceroy of New Spain.

He made his formal entry into Mexico City on October 26, 1603, accompanied by his wife Ana de Mendoza, and assumed the reins of government.

He immediately accused his predecessor, Gaspar de Zúñiga y Acevedo, Count of Monterrey of excessive spending and of exceeding his authority.

Mendoza y Luna also constructed an aqueduct on stone arches that conducted water from the springs on Chapultepec to the center of the city.

On November 20, 1606, Mendoza y Luna was named viceroy of Peru, with instructions to remain in New Spain until the arrival of his successor.

The new viceroy, Luis de Velasco, 1st Marquess of Salinas del Río Pisuerga, arrived in July of the following year, and Mendoza sailed from Acapulco for Lima in that month.