Heathrow Terminal 1 is a disused airport terminal at London Heathrow Airport that was in operation between 1968 and 2015. When it was officially opened by Queen Elizabeth II in April 1969 it was the largest new airport terminal in western Europe.

Heathrow Terminal 1 is currently a disused facility that closed to the public in June 2015 to make way for the expansion of Terminal 2 (The Queen's Terminal). As of 2026, the building is in the final stages of a phased demolition plan. While it no longer handles commercial passengers, it serves several vital "behind-the-scenes" functions for the airport. It currently houses the advanced baggage handling system for Terminal 2, capable of processing over 31,000 bags per day. The empty terminal space is also frequently utilized by emergency services and airport staff for realistic training exercises and security drills. Heathrow's long-term master plan involves completely removing the remaining structures of Terminal 1 to allow for the construction of a new "contact pier" and additional aircraft stands, which will significantly increase the capacity and punctuality of Terminal 2. By 2026, much of the site has been reclaimed for these infrastructure upgrades, signaling the total end of the terminal that once stood as the largest in Western Europe.