Hicksville is a hamlet and census-designated place (CDP) within the Town of Oyster Bay in Nassau County, on Long Island, in New York. The population of the CDP was 43,869 at the 2020 United States census.

Hamlet namesake Valentine Hicks was the son-in-law of abolitionist and Quaker preacher Elias Hicks, and eventual president of the Long Island Rail Road. He bought land in the village in 1834 and turned it into a station stop on the LIRR in 1837. The station became a depot for produce, particularly cucumbers for a Heinz Company plant. After a blight destroyed the cucumber crops, the farmers grew potatoes. It turned into a bustling New York City suburb in the building boom following World War II.

In 1953, Hicksville attempted to incorporate itself as the Incorporated Village of Hicksville. Many residents felt that by incorporating as a village, the community would be run more effectively than by the Town of Oyster Bay. A petition had been signed with 6,242 signatures from residents in favor of the plan.

However, these plans were unsuccessful, and Hicksville remains an unincorporated area of the Town of Oyster Bay to this day, as of 2023.

According to the United States Census Bureau, the CDP has a total area of 6.8 square miles (18 km2), of which 6.8 square miles (18 km2) is land and 0.15% is water.

The climate is borderline between hot-summer humid continental (Dfa) and humid subtropical (Cfa) and the local hardiness zone is 7a. Average monthly temperatures in the village center range from 31.9 Â°F in January to 74.7 Â°F in July.

Metalab Equipment Company, a division of Norbute Corp, made laboratory furniture and cabinetry. Alsy Manufacturing manufactured electric lamps and lampshades from 1975 through 1991.

The Rubber Company of America (RUCO) built a manufacturing site in 1945. RUCO Polymer Corp. (Hooker Chemical Company) manufactured plastics, latex, and esters. Occidental Chemical Corporation (OCC) owned and operated this site from 1966 to 1982. The site was purchased by Sybron Corporation, then in 2000, the Bayer Corporation (Bayer MaterialScience) purchased the Hooker Ruco facility and in 2002 decided to close the facility. The facility was a freight customer of the Long Island Rail Road and New York and Atlantic Railway, served by a spur track off the Main Line next to the grade crossing at New South Road. The site was used for the production of polyester from 1982 until 2002. The LIRR removed the switch during track work sometime after the closure and demolition of the buildings on the property. The property remains fenced-off and vacant currently.

The presence of a major LIRR hub means that Hicksville developed as a major bedroom community of New York City. The LIRR has a team yard on West John Street, just east of Charlotte Avenue, served by the New York and Atlantic Railway, for off-line freight customers receiving or shipping cargo by rail to anywhere in the North American rail network.

Hicksville's North Broadway, positioned in the center of Nassau County, developed into a significant retail center. North Broadway was home to the Mid-Island Shopping Plaza (now known as Broadway Mall), a 156,000-square-foot Sears department store and auto center (which closed in 2018) and various other restaurants and retail stores.

Hicksville is home to a number of South Asian grocery stores, clothing shops and restaurants, due to its large proportion of immigrants from India, Pakistan, and Bangladesh.

As of the 2020 United States Census, there were 43,869 people, and 13,409 households residing in the CDP. The population density was 6,458.9 people per square mile.

The racial makeup of the CDP was 47.2% White, 32.8% Asian, 3.4% African American, 0.2% Native American, 6.9% from two or more races, and Hispanic or Latino of any race were 13.6% of the population.

For the period 2017–2021, the median annual income for a household in the CDP was $123,230. The per capita income for the CDP was $46,504. About 4.1% of people were below the poverty line.

By 1996 there were around four to five restaurants in Hicksville serving South Asian cuisine, and this started the ascent of a "Little India" there.

Between 2010 and 2020, Asian populations in Hicksville grew faster than the population as a whole. During this period, Hicksville's Asian population grew from 8,139 to 14,178, comprising 32.3% of the town's population. By 2020, Hicksville had become "a hub" of Indian-American life, with multiple South Asian grocery stores, clothing shops, and restaurants, serving the religious, economic, financial, and cultural needs of its many South Asian residents.

Hicksville is primarily located within the boundaries of the Hicksville Union Free School District. However, a small part of the hamlet's southeastern corner is located within the boundaries of the Bethpage Union Free School District while a small portion of the hamlet's northeastern corner is located within the boundaries of the Syosset Central School District. As such, children who reside within Hicksville and attend public schools go to school in one of these three districts depending on where they live within the hamlet. In 2023, Hicksville High School was ranked in the top 30% of New York schools by the National Center for Education Statistics.

Hicksville is located within the boundaries of (and is thus served by) the Hicksville Library District, the Bethpage Library District, and the Syosset Library District. The boundaries of these three districts within the hamlet roughly correspond to those of the three school districts.

Four state-owned roads pass through the hamlet: New York State Route 106, New York State Route 107, the Northern State Parkway, and the Wantagh State Parkway. Additionally, the Northern State Parkway forms portions of the hamlet's northern border.

Other major roads within the hamlet include Jerusalem Avenue, Old Country Road, Plainview Road, and South Oyster Bay Road.

Hicksville is a major hub on the Long Island Rail Road, where the Ronkonkoma Branch meets with the Port Jefferson Branch to form the Main Line.

The area is also a hub for the following routes operated by Nassau Inter-County Express: