Charleroi (French pronunciation: [ʃaʁləʁwa], "King Charles", Walloon: Tchålerwè) is a city and a municipality of Wallonia, located in the province of Hainaut, Belgium. As of 1 January 2008 (2008 -01-01)^[update], the total population of Charleroi was 201,593. The metropolitan area, including the outer commuter zone, covers an area of 1,462 square kilometres (564 sq mi) and had a total population of 522,522 as of 1 January 2008, ranking it as the fifth most populous in Belgium after Brussels, Antwerp, Liège and Ghent. The inhabitants are called Carolorégiens or simply Carolos.

The municipality of Charleroi straddles both banks of the river Sambre in an area marked by industrial activities (coal mining and steel industry): the so-called Pays Noir ("black country"), part of the larger sillon industriel. Although most of the factories have closed since the 1950s, the landscape remains dotted with spoil tips and old industrial buildings.

Charleroi lies around 50 kilometres (31 mi) south of Brussels.