Diss is a market town and electoral ward in Norfolk, England, close to the border with the neighbouring East Anglian county of Suffolk, with a population of 7,572 (2011). Diss railway station is on the Great Eastern Main Line, which runs from London to Norwich.
The town lies in the valley of the River Waveney, around a mere that covers 6 acres (2.4 ha). The mere is up to 18 feet (5.5 m) deep, although there is another 51 feet (16 m) of mud.
The town takes its name from dic an Anglo-Saxon word meaning either ditch or embankment. Diss has a number of historic buildings, including an early 14th-century parish church, and a museum.