O'Brien is a city in Haskell County, Texas, United States. The population was 132 at the time of the 2000 census. As of 2010, the O'Brien population was 106. O'Brien is located at the junction of Farm to Market Road 2229 and Texas State Highway 6; the nearest large city is Abilene, 70 miles to the south. The area was hit by a destructive and deadly F4 tornado on March 13, 1953.

Haskell County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 5,416. The county seat is Haskell. The county was created in 1858 and later organized in 1885. It is named for Charles Ready Haskell, who was killed in the Goliad massacre.