Nicolaes Geelvinck (11 October 1706, in Amsterdam – 15 June 1764, in Amsterdam) was lord of Castricum, Bakkum, Santpoort, Velsen, Stabroek, schepen, and owner of the country estate Akerendam-by-Beverwijk. He was appointed as mayor of Amsterdam in 1747, but in 1748 lost his seat in the vroedschap and as a counsellor to the Admiralty of Amsterdam, thanks to Mattheus Lestevenon.
In 1729 Nicolaes Geelvinck married Johanna Jacoba Graafland. His father Lieve Geelvinck married Johanna's mother Anna de Haze the year after. Nicolaes worked at the townhall as a lawyer and city secretary. In 1737 he became administrator WIC, a position held for life. When his wife died in 1740, Nicolaes remarried in 1743 to Hester Hooft, at that time held to be the most beautiful woman in Amsterdam, who died two months later of a spleen disease. His childless sister and a widow perhaps took her place as mother, for Nicolaes had five children to bring up. In 1747 Nicolaes Geelvinck married for the third time, to the only daughter of mayor Gerrit Corver. She brought a million guilders with her and on the death of her father she inherited another 1.1 million. Nicolaes had other reasons to be happy, for - not yet forty - he had just become mayor, and was expected to make reforms to the Admiralty.
On 9 November 1747, during the Taxleasers uproar, Nicolaes Geelvinck - the only burgomaster present - quickly had to flee the city hall on Dam Square, before the mayors room was occupied by the people and a ceiling mob was stuck from the window to make clear, the place was cleaned. The people regarded the leaseholders as responsible, and the regenten's oligarchy as the cause of their misery. The Amsterdam mayors suffered from much criticism, though there were promises that the leasing system would be revised.