Millwood is a hamlet and census-designated place located in the town of New Castle, New York, United States in Westchester County. It was originally settled as Sarlesville. The area now known as Millwood appears on 19th century maps as Merritt's Corners and Rockdale Mills. As of the 2000 census, the community had a population of 1,210. Miss America 1984, actress and singer Vanessa Williams grew up in Millwood, but lives in New Castle's larger hamlet of Chappaqua.