Waterford, meaning "ram (wether) fjord") is a city in Ireland. It is in County Waterford in the south-east of Ireland and is located in the province of Munster. The city is situated at the head of Waterford Harbour. It is the oldest and the fifth most populous city in the Republic of Ireland. It is the tenth most populous settlement on the island of Ireland. Waterford City and County Council is the local government authority for the city. According to the 2016 Census, 53,504 people live in the city, with a wider metropolitan population of 82,963.

Today, Waterford is known for Waterford Crystal, a legacy of the city's former glassmaking industry. Glass, or crystal, was manufactured in the city from 1783 until early 2009, when the factory there was shut down after the receivership of Waterford Wedgwood plc. The Waterford Crystal visitor centre in the Viking Quarter, under new owners, opened in June 2010, after the intervention of Waterford City Council and Waterford Chamber of Commerce, and resumed production. Waterford is also known for being the starting point of Ryanair's first flight, a 14-seat Embraer Bandeirante turboprop aircraft flying between Waterford and Gatwick Airport.

The city is situated at the head of Waterford Harbour. The city motto Urbs Intacta Manet Waterfordia ("Waterford remains the untaken city") was granted by King Henry VII of England in 1497 after Waterford refused to recognise the claims of the pretenders Lambert Simnel and Perkin Warbeck to the English throne. Waterford was subjected to two sieges in 1649 and 1650, during the Cromwellian conquest of Ireland. It withstood the first siege but surrendered during the second siege to Henry Ireton on 6 August 1650.

Reginald's Tower is the oldest urban civic building in Ireland, and the oldest monument to retain its Viking name. To this day, it remains Waterford's most recognisable landmark. It is believed to be the first building in Ireland to use mortar. The River Suir, which flows through Waterford City, has provided a basis for the city's long maritime history. The place downriver from Waterford where the Nore and the Barrow join the River Suir is known in Irish as Cumar na dTri Uisce ("The confluence of the three waters"). Waterford Port has been one of Ireland's major ports for over a millennium. In the 19th century, shipbuilding was a major industry. The owners of the Neptune Shipyard, the Malcomson family, built and operated the largest fleet of iron steamers in the world between the mid-1850s and the late 1860s, including five trans-Atlantic passenger liners.

Waterford is also known for being the "starting point" of one of the biggest European airlines (as of 2013) - Ryanair's first flight was a 14-seat Embraer Bandeirante turboprop aircraft, flying between Waterford and Gatwick Airport.