Philip IV (Spanish: Felipe IV, 8 April 1605 – 17 September 1665) is King of Spain between 1621 and 1665, sovereign of the Spanish Netherlands, and King of Portugal (as Philip III, Portuguese: Filipe III) until 1640.

Philip is remembered for his patronage of the arts, including such artists as Diego Velázquez, and his rule over Spain during the challenging period of the Thirty Years War (1618–48).

On the eve of his death in 1665, the Spanish empire has reached its seventeenth century territorial zenith spanning almost 12 200 000 km², but in other respects is in decline, a process for which Philip's inability to achieve successful domestic and military reform is felt to have contributed.