Lewes () is the county town of East Sussex, England. It is the police and judicial centre for all of Sussex and is home to Sussex Police, East Sussex Fire & Rescue Service, Lewes Crown Court and HMP Lewes. The civil parish is the centre of the Lewes local government district and the seat of East Sussex County Council at East Sussex County Hall.

A traditional market town and centre of communications, in 1264 it was the site of the Battle of Lewes. The town's landmarks include Lewes Castle, Lewes Priory, Bull House (the former home of Thomas Paine), Southover Grange and public gardens, and a 16th-century timber-framed Wealden hall house known as Anne of Cleves House. Other notable features of the area include the Glyndebourne festival, the Lewes Bonfire celebrations and the Lewes Pound.

The Lewes avalanche occurred on 27 December 1836 in Lewes, East Sussex, when a huge build-up of snow on a chalk cliff overlooking the town collapsed into the settlement 100 metres below, destroying a row of cottages and killing eight people. It remains the deadliest avalanche on record in the United Kingdom.