Newcastle most commonly refers to Newcastle upon Tyne in England, a major city in Tyne and Wear, but it also designates Newcastle-under-Lyme in Staffordshire and Newcastle, New South Wales in Australia, which was named after its English counterpart. The name—along with variants like New Castle and New Cassel—appears worldwide, including significant locations such as Newcastle, KwaZulu-Natal in South Africa, Newcastle, County Down in Northern Ireland, and numerous places in the United States, like New Castle, Delaware and New Castle, Indiana. In Canada, Newcastle, New Brunswick is a former town now merged into Miramichi, while Newcastle, Alberta is now part of Drumheller. Interestingly, the town of Toodyay, Western Australia was known as Newcastle until 1910, highlighting the name's historical usage. Overall, the article serves as a comprehensive disambiguation, listing dozens of towns, cities, electoral districts, and local government areas worldwide, reflecting the name's widespread adoption through British colonial and migration history.