Gaspar de Guzmán y Pimentel Ribera y Velasco de Tovar, Count-Duke of Olivares and Duke of San Lúcar la Mayor (Spanish: Gaspar de Guzmán y Pimentel, conde-duque de Olivares, also known as Conde de Olivares y duque de Sanlúcar la Mayor) (January 6, 1587 – July 22, 1645), is a Spanish royal favorite of Philip IV and minister.

As prime minister from 1621 to 1643, he overexerts Spain in foreign affairs and unsuccessfully attempts domestic reform.

His policies of committing Spain to recapture Holland lead to his major involvement in the Thirty Years War (1618–1648) and his attempts to centralize power and increase wartime taxation lead to revolts in Catalonia and Portugal which bring about his fall.