Gaspar de Guzmán y Pimentel, 1st Duke of Sanlúcar, 3rd Count of Olivares,, known as the Count-Duke of Olivares, was a Spanish royal favourite of Philip IV and minister. Appointed as Grandee on 10 April 1621, a day after the ending of the Twelve Years' Truce to January 1643, he over-exerted Spain in foreign affairs and unsuccessfully attempted domestic reform. His policy of committing Spain to recapture Holland led to a renewal of the Eighty Years' War while Spain was also embroiled in the Thirty Years' War (1618–1648). In addition, his attempts to centralise power and increase wartime taxation led to revolts in Catalonia and in Portugal, which brought about his downfall.

A favourite was the intimate companion of a ruler or other important person. In post-classical and early-modern Europe, among other times and places, the term was used of individuals delegated significant political power by a ruler. It was especially a phenomenon of the 16th and 17th centuries, when government had become too complex for many hereditary rulers with no great interest in or talent for it, and political institutions were still evolving. From 1600 to 1660 there were particular successions of all-powerful minister-favourites in much of Europe, particularly in Spain, England, France and Sweden.