O'Brien is an unincorporated community and census-designated place (CDP) in Josephine County, Oregon, United States. As of the 2010 census, O'Brien had a population of 504. The unemployment rate is 6.9%, slightly higher than the national average of 5.2% The community was named after John O'Brien, who was one of the first settlers to arrive at the locality. In 2012, a small group started protecting the town when the police were cut due to budget cuts.