Cornelis de Graeff, also Cornelis de Graeff van (Zuid-)Polsbroek (15 October 1599 – 4 May 1664) was the most illustrious member of the De Graeff family. He was a mayor of Amsterdam from the Dutch Golden Age and a powerful Amsterdam regent after the sudden death of stadholder William II of Orange, during the First Stadtholderless Period. Like his father Jacob Dircksz de Graeff, he opposed the house of Orange, and was the moderate successor to the republican Andries Bicker. In the mid 17th century he controlled the city's finances and politics and, in close cooperation with his brother Andries de Graeff and their nephew Johan de Witt, the Netherlands political system.