Waterloo station (), also known as London Waterloo, is a central London terminus on the National Rail network in the United Kingdom, in the Waterloo area of the London Borough of Lambeth. It is connected to a London Underground station of the same name and is adjacent to Waterloo East station on the South Eastern Main Line. The station is the terminus of the South West Main Line to Weymouth via Southampton, the West of England main line to Exeter via Salisbury, the Portsmouth Direct line to Portsmouth Harbour which connects with ferry services to the Isle of Wight, and several commuter services around west and south-west London, Surrey, Hampshire and Berkshire.

The station was opened in 1848 by the London and South Western Railway, and it replaced the earlier Nine Elms as it was closer to the West End. It was never designed to be a terminus, as the original intention was to continue the line towards the City of London, and consequently the station developed in a haphazard fashion, leading to difficulty finding the correct platform. The station was rebuilt in the early 20th century, opening in 1922, and included the Victory Arch over the main entrance, which commemorated World War I. Waterloo was the last London terminus to provide steam-powered services, which ended in 1967. The station was the London terminus for Eurostar international trains from 1994 until 2007, when they were transferred to St. Pancras.

Waterloo is one of the busiest railway stations in the UK, and has had nearly a hundred million entries and exits from the station in a year. It is also the country's largest station in terms of floor space and has the greatest number of platforms.