East Islip is a hamlet and CDP in the Town of Islip, Suffolk County, New York, United States. At the time of the2010 census, the CDP had a population of 14,475.
Originally referred to as "East of Islip", the name was acquired in 1890 from the estate of William Nicoll, anEnglish aristocrat who purchased the surrounding land in 1683 to erect a family residence. Nicoll's purchase comprised 51,000 acres (210 km2) from the Secatogue Indians, reaching as far as Bayport to the east,Babylon to the west and Ronkonkoma to the north. His mansion, Islip Grange, named after his family's ancestral estate at Northampshire, England, stood near the shoreline of what is now Heckscher State Park. East Islip, as well as many hamlets along Long Island's south shore, was once an enclave for some of the nation's wealthiest families. Its estates at one time included the Hollins, Gulden, and Knapp estates, among others.