Roslyn is a village in the Town of North Hempstead in Nassau County, on the North Shore of Long Island, in New York, United States. It is the Greater Roslyn area's anchor community. The populatio…Roslyn is a village in the Town of North Hempstead in Nassau County, on the North Shore of Long Island, in New York, United States. It is the Greater Roslyn area's anchor community. The population was 2,770 at the 2010 census.