Hillside Manor is an unincorporated hamlet in the Town of North Hempstead in Nassau County, on Long Island, in New York, United States, within the census-designated place (CDP) of Garden City Park.

Although presently considered part of the Garden City Park CDP, the name continues to be widely used and accepted both socially and politically – most notably by the Hillside Manor Post Office.

When the post office was first unveiled in November 1948, the stone nameplate on the building erroneously said "Garden City Park" due to an error on the blueprints, causing a massive uproar from local residents as well as from the press; the engraving on the nameplate was soon corrected to display the name "Hillside Manor.

"[2][3][4] According to the United States Geological Survey, Hillside Manor has an elevation of 98 feet (30 m).

[6] Hillside Manor is located within the Garden City Park CDP.