Newcastle
- County:
- McClain County
- County Seat:
- No
- Area (mi²):
- 60.057
- State:
- Oklahoma
Newcastle is a city located in McClain County, Oklahoma. Newcastle has a 2026 population of 14,677. Newcastle is currently growing at a rate of 4.95% annually and its population has increased by 31.4% since the most recent census, which recorded a population of 11,170 in 2020.