Leo F. O'Brien (June 26, 1924 – March 21, 1968) was an American lawyer and politician.
He went to Corpus Christi High School and to Knox College.
O'Brien served in the United States Army during World War II and was commissioned a sergeant.
O'Brien served in the Illinois House of Representatives from 1965 until his death in 1968 and was a Democrat.
O'Brien died in an automobile accident while driving in Galesburg, Illinois on U.S. Route 150.