List of law enforcement agencies on Long Island

The List of Long Island law enforcement agencies provides an inclusive list of law enforcement agencies serving New York's Long Island. This includes those agencies serving the New York City boroughs of Brooklyn and Queens on the western portion of Long Island along with those serving the suburban counties of Nassau County and Suffolk County.

New York City

• New York City Police Department
• New York City Sheriff's Office (peace officers)
• New York City Marshals (peace officers)
• New York City Department of Environmental Protection Police (peace officers)
• New York City Department of Sanitation Police (peace officers)
• New York City Department of Health and Hospitals Police (peace officers)
• New York City Parks Enforcement Patrol (peace officers)
• New York City Taxi and Limousine Commission Inspectors (peace officers)
• New York City Department of Investigation
• New York City Department of City Administrative Services Police (peace officers)
• New York City Department of Correction (peace officers)
• New York City Department of Human Resource Services Police (peace officers)
• New York City Department of Homeless Services Police (peace officers)
• City University of New York Public Safety Department (peace officers)
• New York Public Safety(private police force for the Big Six Towers housing community)(peace officers)
• Co-Op City Police Department (private police force for Bronx housing project)(peace officers)
• Roosevelt Island Department of Public Safety (private police force for Roosevelt Island Development Corps owned housing projects)(peace officers)
• Seagate Police Department (private police force for Brooklyn/Coney Island community)(peace officers)
• Triborough Bridge and Tunnel Authority officers (Peace Officers)
• Port Authority of New York and New Jersey Police Deparment
• American Society for the Prevention of Cruelty to Animals Law Enforcement officers (peace officers)
• New York Society for the Prevention of Cruelty to Children Law Enforcement officers (peace officers)

The New York City Transit Police and the New York City Housing Authority Police were merged into the NYPD in 1995. The Brooklyn Police Department and the Long Island City Police Department in 1898 and the Town of Morrisania Police Department in 1879.

Each of the five counties of New York City — New York (Manhattan), Bronx, Richmond (Staten Island), Kings (Brooklyn) and Queens — had a county sheriff's department. In 1942 they were merged together to form the New York City Sheriff's Office. In 1939 the corrections part of the individual county sheriff's office's became the separate New York City Department of Correction.

Nassau County

• Nassau County Police Department
  • Nassau County Police Public Safety officers (peace officers)
• Nassau County Sheriff's Department
• Nassau County Community College Department of Public Safety (peace officers)
• Nassau County Fire Marshals (peace officers)
• Nassau County SPCA Law Enforcement Division (peace officers)

• East Hills Department of Public Safety (peace officers)
• Floral Park Police Department
• Freeport Police Department
• Garden City Police Department
• Glen Cove Police Department
• Great Neck Estates Police Department
• Hempstead Village Police Department
• Kings Point Police Department
• Lake Success Police Department
• Long Beach Police Department
• Lynbrook Police Department
• Malverne Police Department
• Old Westbury Police Department
• Old Brookville Police Department
• Port Washington Police Department
• Oyster Bay Cove Police Department
• Rockville Centre Police Department
• Sands Point Police Department
• Town of Hempstead Bay Constables (peace officers)
• Town of Hempstead Department of Public Safety (peace officers)
• Town of North Hempstead Bay Constables (peace officers)
• Town of North Hempstead Department of Public Safety (peace officers)
• Town of Oyster Bay Bay Constables (peace officers)
• Town of Oyster Bay Department of Public Safety (peace officers)

Suffolk County

• Suffolk County Police Department
  • Babylon Town Police Department - merged to form the SCPD in 1960.
    • Babylon Village Police Department - merged to form the SCPD in 1960.
    • Lindenhurst Police Department - merged to form the SCPD in 1960.
  • Brookhaven Town Police Department - merged to form the SCPD in 1960.
    • Patchogue Village Police Department - merged to form the SCPD in 1960.
  • Islip Town Police Department - merged to form the SCPD in 1960.
    • Brightwaters Police Department - mergead to form the SCPD in 1960.
  • Huntington Town Police Department - merged to form the SCPD in 1960.
  • Smithtown Town Police Department - merged to form the SCPD in 1960.
• Suffolk County Sheriff's Office
• Suffolk County Park Police
  • Suffolk County Park Rangers until 1991
• Suffolk County Community College Office of Public Safety (peace officers)
• Suffolk County SPCA Law Enforcement Division (peace officers)

• Amityville Police Department
• Babylon Village Code Enforcement (peace officers)
• Belle Terre Village Constables (peace officers)
• Brightwaters Village Public Safety (peace officers)
• East Hampton Town Marine Patrol
• East Hampton Town Police Department
• East Hampton Village Police Department
• Fisher's Island Constables (peace officers)
• Head of the Harbor Police Department
• Lloyd Harbor Police Department
• Long Island MacArthur Airport Police Department (peace officers)
• Nissequogue Police Department
• Northport Police Department
• Ocean Beach Police Department
• Old Field Village Constables (peace officers)
• Port Jefferson Village Constables Bureau (peace officers)
• Poquott Village Constables (peace officers)
• Patchogue Village Constables (peace officers)
• Quogue Police Department
• Riverhead Town Police Department
• Sag Harbor Police Department
• Salitare Police Department
• Shelter Island Town Police Department
• Southampton Town Bay Constables
• Southampton Town Police Department
• Southampton Village Police Department
• Southold Town Police Department
• Town of Babylon Bay Constable's Office (peace officers)
• Town of Babylon Park Rangers (peace officers)
• Town of Brookhaven Fire Marshals (peace officers)
• Town of Brookhaven Park Rangers Defunct Agency (peace officers)
• Town of Islip Fire Marshal's Office (peace officers)
• Town of Islip Harbor Police Department (peace officers)
• Town of Islip Park Rangers (peace officers)
• Town of Huntington Harbormaster/Bay Constables(peace officers)
• Town of Smithtown Department of Public Safety (peace officers)
• Town of Smithtown Park Rangers (peace officers)
• Village of the Branch Police Department
• Westhampton Beach Police Department
• Westhampton Dunes Village Constables (peace officers)

Other

• Long Island Society for the Prevention of Cruelty to Children Law Enforcement (peace officers)
• Long Island State Parkway Police (Defunct)
• New York State Police
• New York State Park Police
• New York State Court Officers (peace officers)
• New York State Department of Environmental Conservation Police
• New York State Office of Mental Health Police
• New York State Office of Mental Retardation and Developmental Disabilities (OMRDD) Police
• Metropolitan Transportation Authority Police
• State University of New York at Stony Brook Police Department
• SUNY Farmingdale Police Department
• SUNY Old Westbury Police Department

Federal

• Bureau of Alcohol, Tobacco, Firearms and Explosives
• Drug Enforcement Administration
• Federal Bureau of Investigation
• Immigration and Customs Enforcement
• US Federal Protective Service
• US Marshal's Service
• US National Park Service (Law Enforcement Rangers)
• US Park Police
• US Postal Inspection Service
• US Postal Police
• US Probation and Parole Department
• US Secret Service
• US Veterans Affairs Police Department (at the Northport VA Hospital)