Newcastle usually refers to:
- Newcastle upon Tyne, a city and metropolitan borough in Tyne and Wear, England, United Kingdom
- Newcastle-under-Lyme, a town in Staffordshire, England, United Kingdom
- Newcastle, New South Wales, a metropolitan area in New South Wales, Australia, named after Newcastle upon Tyne
Newcastle, New Castle or New Cassel may also refer to:
Australia
- City of Newcastle, a local government area in New South Wales
- County of Newcastle, a cadastral unit in South Australia
- Division of Newcastle, a federal electoral division in New South Wales
- Electoral district of Newcastle, an electoral district of the New South Wales Legislative Assembly
- Electoral district of Newcastle (South Australia) 1884–1902, 1915–1956 in the South Australian House of Assembly
- Newcastle, New South Wales, a city in New South Wales
- Newcastle Waters, a town and locality in the Northern Territory
- Newcastle West, New South Wales, inner suburb of the city
- Toodyay, Western Australia, known as Newcastle until 1910
Canada
- Newcastle, Alberta, a former village now within the Town of Drumheller
- Newcastle, New Brunswick, a former town, now part of Miramichi
- Newcastle, Ontario, a community in the Municipality of Clarington in Durham Region
- Newcastle District, a historic district in Upper Canada which existed until 1849
- Newcastle Parish, New Brunswick
- Newcastle (electoral district), a provincial electoral district in the Canadian province of British Columbia
Republic of Ireland
- Newcastle, Clonfad, a townland in Clonfad civil parish, barony of Fartullagh, County Westmeath
- Newcastle, County Tipperary
- Newcastle, County Wicklow
- Newcastle, Dublin
- Newcastle, Kilcleagh, a townland in Kilcleagh civil parish, barony of Clonlonan, County Westmeath
- Newcastle, Lickbla, a townland in Lickbla civil parish, barony of Fore, County Westmeath
- Newcastle West, County Limerick
United Kingdom
Northern Ireland
- Newcastle, County Down, a small town in County Down lying at the foot of the Mourne Mountains an area of outstanding natural beauty.
United States
- New Castle, Alabama, an unincorporated community in Jefferson County
- Newcastle, California, an unincorporated town in Placer County
- New Castle, Colorado, a home rule municipality in Garfield County
- New Castle, Delaware, a city in New Castle County
- New Castle County, Delaware, the northernmost of the three counties
- New Castle Hundred, an unincorporated subdivision of New Castle County, Delaware
- New Castle, Indiana, a city in Henry County
- Webster City, Iowa, formerly Newcastle, county seat of Hamilton County
- New Castle, Kentucky, a city in Henry County
- Newcastle, Maine, a town in Lincoln County
- Newcastle, Nebraska, a village in Dixon County
- Newcastle Township, Dixon County, Nebraska, a township in Dixon County
- New Castle, New Hampshire, a town in Rockingham County
- New Cassel, New York, an unincorporated place in Nassau County
- New Castle, New York, a town in Westchester County
- New Castle, Ohio, an unincorporated community in Belmont County
- Newcastle, Ohio, an unincorporated community in Coshocton County
- Newcastle Township, Coshocton County, Ohio, one of the twenty-two townships of Coshocton County
- Newcastle, Oklahoma, the largest city in McClain County
- New Castle, Pennsylvania, a city in Lawrence County
- New Castle Northwest, Pennsylvania, a census-designated place in Lawrence County
- New Castle Township, Pennsylvania, a township in Schuylkill County
- South New Castle, Pennsylvania, a borough in Lawrence County
- Newcastle, Texas, a city in Young County
- Newcastle, Utah, an unincorporated community in southwestern Iron County
- New Castle, Virginia, the only town in Craig County
- Newcastle, Washington, a city in King County
- New Cassel, Wisconsin, a former village in Fond du Lac County
- Newcastle, Wyoming, a city located in Weston County
- Newcastle Castle, Bridgend, a medieval castle in Wales
- New Castle Correctional Facility, a prison located in New Castle, Indiana
- Newcastle International Sports Centre, a stadium in Newcastle, New South Wales
- New Castle School of Trades, a technical trades school in Pulaski, Pennsylvania
- New Palace (Stuttgart) (Das Neues Schloss, sometimes translated as the "New Castle"), a palace in Stuttgart, Germany
- Akhaltsikhe ("New Castle"), Georgia
- Castelnau (disambiguation) ("New Castle"), places in Occitan-speaking areas
- Castelnuovo (disambiguation) ("New Castle"), places in Italian-speaking areas
- Châteauneuf (disambiguation) ("New Castle"), places in French-speaking areas
- Herceg Novi ("New Castle"), Montenegro (formerly Italian Castelnuovo)
- Jaunpils ("New Castle"), Latvia
- Kaštel Novi ("New Castle"), Croatia
- Kota Bharu ("New Castle"), Malaysia
- Neuburg (disambiguation) ("New castle"), places in German-speaking areas
- Neuchâtel (disambiguation) ("New castle"), places in French-speaking areas
- Neufchâtel (disambiguation) ("New castle"), places in French-speaking areas
- Newport, Wales, Casnewydd-ar-Wysg ("New castle-on-Usk") in Welsh
- Nové Zámky ("New Castle"), Slovakia
- Nowy Zamek ("New Castle"), Poland (formerly German Neuschloß)
- Nyborg ("New Castle"), Denmark
- Qaleh Now (disambiguation) ("New Castle"), places in Persian-speaking areas
- Shinshiro ("New Castle"), Japan
- Tazeh Qaleh (disambiguation) ("New Castle"), places in Azeri- and Turkmen-speaking areas