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:

• 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

• 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

• Newcastle, Clonfad, a townland in Clonfad civil parish, barony of Fartullagh, County Westmeath
• Newcastle, County Tipperary
• Newcastle, County Wicklow
• Newcastle, County 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

• Newcastle, Jamaica

• Newcastle, Saint Kitts and Nevis

• Newcastle, KwaZulu-Natal, a city in northern KwaZulu-Natal
• Newcastle Local Municipality, administrative area in the Amajuba district in KwaZulu-Natal

• Newcastle, Shropshire (Newcastle on Clun), a village (and parish) in south Shropshire
• Newcastle-under-Lyme, the principal town of the Borough of Newcastle-under-Lyme, Staffordshire
  • Borough of Newcastle-under-Lyme, a local government district with borough status in Staffordshire
  • Newcastle-under-Lyme (UK Parliament constituency), a constituency represented in the House of Commons
  • Newcastle-under-Lyme Rural District, a rural district in the county of Staffordshire
• Newcastle upon Tyne, a city in Tyne and Wear
  • Newcastle-upon-Tyne (UK Parliament constituency), a former borough constituency in the county of Northumberland

• Newcastle, County Down, a small town in County Down lying at the foot of the Mourne Mountains

• Newcastle, Monmouthshire
• Newcastle, Bridgend, an area and electoral ward
• Newcastle Emlyn, Carmarthenshire

• New Castle, Alabama, an unincorporated community in Jefferson County
• Newcastle, California, an unincorporated community 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 Delaware's 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 (CDP), Maine, the main village in the town
• 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, a township in 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 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 (film), a 2008 Australian film
• Newcastle Publishing Company, a Southern California-based small trade paperback publisher
• "Newcastle" (The Architecture the Railways Built), a 2021 television episode
• Newcastle, a playable character in the game Apex Legends

• Newcastle Castle, Bridgend, a medieval castle in Wales
• New Castle Correctional Facility, a prison located in New Castle, Indiana
• New Palace (Stuttgart) (Das Neues Schloss, sometimes translated as the "New Castle"), a palace in Stuttgart, Germany

• Newcastle Jets FC, an Australian association football club in Newcastle, NSW
• Newcastle United F.C., an English association football club based in Newcastle upon Tyne
• Newcastle Falcons, an English rugby union club based in Newcastle upon Tyne
• Newcastle Knights, an Australian rugby league team based in Newcastle, New South Wales
• Newcastle Thunder, an English rugby league club based in Newcastle upon Tyne

• Newcastle Eagles, the most successful team in the history of the British Basketball League (BBL)

• Newcastle Airport, several airports of this name
• Newcastle International Airport, airport of Newcastle-upon-Tyne, England
• New Castle Airport, a public airport located in an unincorporated part of New Castle County, Delaware, United States

• New Castle District, a railroad line owned and operated by the Norfolk Southern Railway in Ohio and Indiana, United States
• Newcastle railway line, New South Wales, Australia, running from Broadmeadow

• HMAS Newcastle, an Adelaide class frigate of the Royal Australian Navy
• HMS Newcastle, a name given to eight ships of the British Royal Navy
• Newcastle (clipper), 1857 English ship

• Duke of Newcastle, a title in the UK
• Newcastle Building Society, a British financial institution
• Newcastle, an Athlon 64 computer processor core revision

• 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