Frederick Philipse III (September 20, 1720 – April 30, 1785) was the third and last Lord of Philipsburg Manor, a 52,000 acres (21,000 ha) hereditary estate in lower Westchester County, New York, and a Loyalist during the Revolutionary War.

[1] John Jay, a Founding Father of the United States who was the co-author of the Treaty of Paris and the Federalist Papers, as well as the first Chief Justice of the Supreme Court and second American Governor of New York, was a cousin, on his maternal side.

Philipse integrated himself and his wife into Loyalist society, purchased commissions in the British army for his five sons, and their daughters were "the talk of New York's winter balls as they had been in pre-war days".

[3]: 27 Victim of an effort led by his own cousin, John Jay,[3]: 28  Philipse was attainted by the Provincial Congress of New York in 1779 and his Manor and other lands in today's Westchester County were seized.

In spite of assurances of restitution in the 1783 Treaty of Paris signed with the British,[8] and the enormous sum raised – the better part of a quarter of a million pounds Sterling[9] – New York's Provisional Congress reneged and no payment from them was forthcoming.

[3]: 31 Historian Beatrice G. Reubens argues that the confiscation of Loyalist estates was a major reform for social and economic equality upstate New York.

After losing his New York holdings due to his loyalist stance during the American Revolution, Frederick III and his family relocated to the area, where he spent the remainder of his life.