Heathrow Airport (), called London Airport until 1966 (IATA: LHR, ICAO: EGLL), is the main international airport serving London, the capital of England and the United Kingdom. It is the largest of the six international airports in the London airport system (the others being Gatwick, City, Luton, Stansted and Southend). The airport is owned and operated by Heathrow Airport Holdings, owned mostly by Qatar Investment Authority, Public Investment Fund and CDPQ. In 2023, Heathrow was the busiest airport in Europe, the fourth-busiest airport in the world by passenger traffic and the second-busiest airport in the world by international passenger traffic. As of 2023, Heathrow is the airport with the most international connections in the world.

Heathrow was founded as a small airfield in 1930 but was developed into a much larger airport after World War II. It lies 14 miles (23 kilometres) west of Central London on a site that covers 4.74 square miles (12.3 square kilometres). It was gradually expanded over 75 years and now has two parallel east–west runways, four operational passenger terminals and one cargo terminal. The airport is the primary hub for British Airways and Virgin Atlantic.