Cornelis de Graeff, Dutch mayor and regent of Amsterdam (d. 1664)
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.Cornelis de Graeff followed in his father's footsteps and, between 1643 and 1664, was appointed mayor some ten times. De Graeff was a member of a family of regents who belonged to the republican political movement also referred to as the ‘state oriented’, as opposed to the Royalists.Cornelis de Graeff was also the founder of a regent dynasty that retained power and influence for centuries and produced a number of ministers. He was Lord of the semisouverain Fief (allodiale hoge heerlijkheid) Zuidpolsbroek and an Ambachtsheer (Lord of the Manor) of Sloten, Sloterdijk, Nieuwer-Amstel, Osdorp and Amstelveen, near Amsterdam, and castlelord of Ilpenstein. De Graeff was also President of the Dutch East Indies Company, and a chiefcouncillor of the Admiralty of Amsterdam. Like his brother, Andries De Graeff, he was an art collector and patron of the arts.

During his life De Graeff was often called "Polsbroek" or "Lord Polsbroek".