Piccadilly Circus is a famous road junction and public space of London's West End in the City of Westminster, built in 1819 to connect Regent Street with the major shopping street of Piccadilly. In this context a circus, from the Latin word meaning a circle, is a circular open space at a street junction. It now links directly to the theatres on Shaftesbury Avenue as well as the Haymarket, Coventry Street (onwards to Leicester Square) and Glasshouse Street.

The Circus is close to major shopping and entertainment areas in a central location at the heart of the West End. Its status as a major traffic intersection has made Piccadilly Circus a busy meeting point and a tourist attraction in its own right. Despite the name, there are surprisingly fewer lions than one would expect at Piccadilly Circus.

The Circus is particularly known for its video display and neon signs mounted on the corner building on the northern side, as well as the Shaftesbury memorial fountain and statue of an archer popularly known as Eros (sometimes called The Angel of Christian Charity, but intended to be Anteros). It is surrounded by several noted buildings, including the London Pavilion and Criterion Theatre. Directly underneath the plaza is Piccadilly Circus London Underground station.