US Congressman. He was born one of two children as Thomas Joseph O'Brien to Thomas O'Brien and his wife Mary Murphy O'Brien in Chicago, Illinois, on April 30, 1878. He was educated locally attending both grade schools and high schools. He then took advanced courses in business law and accounting and eventually became involved in public accountant pursuits in 1918. He then decided to enter politics and was elected as a Member of the Illinois State House of Representatives and served in that post from 1907 to 1910. He also served as the Illinois State Bank Examiner from 1913 to 1924, and another term as a Member of the Illinois State House of Representatives from 1929 to 1932. He then decided to run for a seat in the United States Congress and was elected to succeed the outgoing United States Representative James Thomas Igoe (1883-1971), on March 4, 1933. A Member of the Democratic Party, he then served Illinois' 6th District (Seventy-Third Congress, Seventy-Fourth Congress, and the Seventy-Fifth Congress), in the United States House of Representatives from March 4, 1933, to January 3, 1939. During his time in office of the United States Congress he made headlines when he was arrested in a police raid on a gambling establishment in 1935. He did not seek renomination for another term in 1938. After his term in the United States Congress expired he was succeeded in office by the incoming United States Representative Anton Frank 'A.F.' Maciejewski (1893-1949), on January 3, 1939. After his time in the United States Congress he became a Candidate for the office of Sheriff of Cook County, Illinois, in 1938. He was elected to that post and served as the Sheriff of Cook County, Illinois, from 1938 to 1942. He then decided to run for another seat in the United States Congress and was elected to succeed the outgoing United States Representative Anton Frank 'A.F.' Maciejewski (1893-1949), on January 3, 1943. A Member of the Democratic Party, he then served Illinois' 6th District (Seventy-Eighth Congress, Seventy-Ninth Congress, Eightieth Congress, Eighty-First Congress, Eighty-Second Congress, Eighty-Third Congress, Eighty-Fourth Congress, Eighty-Fifth Congress, Eighty-Sixth Congress, Eighty-Seventh Congress, and the Eighty-Eighth Congress), in the United States House of Representatives from January 3, 1943, to April 14, 1964. He passed away from a stroke in Bethesda, Maryland, on April 14, 1964, at the age of 85, and was buried in Queen Of Heaven Catholic Cemetery in Hillside, Illinois. He was married to Nettie E. Kaufer O'Brien (1879-1972), on July 15, 1920, and she is interred next to her husband. After his death in the office while serving in the United States Congress he was succeeded by the incoming United States Representative Daniel John Ronan (1914-1969), on January 3, 1965. While serving in the United States Congress he was also Delegate to Democratic National Convention from Illinois in 1960, and he was known as the "Dean" of Chicago, Illinois, Delegates and played a pivotal role in the early career of United States Representative Daniel David 'Dan' Rostenkowski (1928-2010). He was also life Member of the Knights of Columbus. The T.J. O'Brien Lock and Dam approximately 7 miles from Lake Michigan on the Calumet River in Chicago, Illinois, at the head of the Illinois Waterway is named in his memory.