Newcastle, also commonly referred to as Greater Newcastle ( NEW-kah-səl; Awabakal: Mulubinba) is a regional metropolitan area and the second-most-populous district of New South Wales, Australia. It includes the cities of Newcastle and Lake Macquarie and it is the hub of the Lower Hunter region, which includes most parts of the cities of Newcastle, Lake Macquarie, Maitland, Cessnock, and Port Stephens Council. Newcastle is also known by its colloquial nickname, Newy.

The metropolitan area of Newcastle is the second-most-populous area in New South Wales to Sydney.

Like most major cities, the Newcastle metropolitan area has an extensive system of both road links and road based public transport services (bus, taxi etc.) which cover most areas of both Newcastle and Lake Macquarie and which extend beyond the metropolitan area itself. Rail transport, however, is accessible to only a relatively small percentage of the population along the major rail transport routes and ferry services are restricted to those commuting between Newcastle and Stockton. Within the metropolitan area the car remains the dominant form of transportation. Newcastle, like all major Australian urban centres, had a tram system, but it was closed in 1950. In February 2019, trams returned to the city with the opening of the Newcastle Light Rail.