O'Brien
- County:
- Haskell County
- County Seat:
- No
- Area (mi²):
- 0.504
- State:
- Texas
O'Brien is a city located in Haskell County, Texas. O'Brien has a 2026 population of 91. O'Brien is currently declining at a rate of 0% annually and its population has increased by 1.11% since the most recent census, which recorded a population of 90 in 2020.