Crook County is a county located in the U.S. state of Oregon. As of the 2010 census, the population was 20,978. The county seat is Prineville. The county is named after George Crook, a U.S. Army officer who served in the American Civil War and various Indian Wars.Crook County comprises the Prineville, OR Micropolitan Statistical Area, which is included in the Bend-Redmond-Prineville, OR Combined Statistical Area.