Transit Police, or Transport Police, are a specialized type of police employed by a common carrier, usually a railroad (but may also include a bus line or other transport carrier) that are tasked to prevent and investigate crimes committed against the carrier or by or against passengers or other customers of the carrier.

A transit police force may consist of officers employed directly by a transit provider, such as the Amtrak Police, or it may exist as a department of another police entity contracted to the transit provider, such as the Transit Police Services Bureau of the Orange County, California Sheriff's Department, which serves the Orange County Transportation Authority.

Where the term transit police is used for the police working for a railroad, it usually refers to a railroad providing urban mass transit (such as a city elevated system or subway) as opposed to long-distance rail carriage. Police who work either for a non-passenger railroad or long-haul rail carrier are usually referred to as Railroad Police or Railway Police.

Some of the crimes Transit Police and Railroad Police investigate include trespassing on the right-of-way of a railroad, assaults against passengers, tagging of graffiti on railroad rolling stock and buses or bus stops, pickpocketing, ticket fraud, robbery and theft of personal belongings, baggage or freight. Depending on the jurisdiction, they may not have any more authority than any other private security firm.

Transit and Railroad Police tend to have better results in finding perpetrators of crimes they investigate than public police forces, possibly due to specialization and smaller case loads.

List of specialised transit/transport police agencies and departments

• Australia
  • Railway Squad, Queensland Police
  • Transit Police Division, South Australia Police (all public transport in Adelaide)
  • Transit Safety Division, Victoria Police (predominantly operate in Melbourne)

• Canada
  • Calgary Transit Protective Services
  • Canadian National Railway Police
  • Canadian Pacific Railway Police
  • Société de transport de Montréal (STM) Security Service
  • Toronto Transit Commission Special Constables
  • TransLink Provincial Special Constables

• Hong Kong
  • Railway District, Hong Kong Police Force

• Italy
  • Railway Police (Polizia Ferroviaria), Polizia di Stato

• Netherlands
  • Railway Police Service (Dienst Spoorwegpolitie), Dutch National Police (Korps Landelijke Politiediensten)

• United Kingdom
  • British Transport Police (national railways in Great Britain, London Underground, Docklands Light Railway, Midland Metro, Tramlink)
  • Metrolink Unit, Greater Manchester Police
  • Metro Unit, Northumbria Police

• United States of America
  • Amtrak Police Department (also police Caltrain)
  • Burlington Northern Santa Fe Railway Police
  • Conrail Railroad Police Department
  • CSX Police Department
  • Dallas Area Rapid Transit (DART) Police Department
  • Greater Cleveland Transit Police Department
  • Hardin Southern Railroad Police Department
  • Metro Transit Police Department, King County Sheriff's Office
  • Transit Services Bureau, Los Angeles County Sheriff's Department
  • Maryland Transit Administration Police Force
  • Massachusetts Bay Transportation Authority Police Department
  • Metropolitan Atlanta Rapid Transit Authority (MARTA) Police Department
  • Metropolitan Transit Authority of Harris County (METRO) Transit Police Department
  • New Jersey Transit Police Department
  • Transit Bureau, New York City Police Department (New York Subway)
  • New York, Susquehanna and Western Railroad Police Department
  • Niagara Frontier Transportation Authority Transit Police Department
  • Norfolk Southern Railway Police Department
  • Northern Indiana Transportation District Transit Police Department (South Shore Line )
  • OCTA-Transit Police Services Bureau, Orange County Sheriff's Department
  • Port Authority of New York and New Jersey Police Force (PATH)
  • MetroLink Unit, St. Louis County Police Department
  • San Francisco Bay Area Rapid Transit (BART) District Police Department
  • Southeastern Pennsylvania Transit Authority (SEPTA) Police Department
  • State of New York Metropolitan Transportation Authority Police Department
  • Union Pacific Railroad Police Department
  • Washington Metro Transit Police Department