Lilius Bratton Rainey (July 27, 1876 – September 27, 1959) was a U.S. Representative from Alabama.
Born in Dadeville, Alabama, Rainey attended the common schools. He moved to Fort Payne, Alabama. He graduated from the Alabama Polytechnic Institute, Auburn, Alabama, in 1899 and from the law department of the University of Alabama at Tuscaloosa in 1902. He was admitted to the bar in the latter year and commenced practice in Gadsden, Alabama.
Rainey was elected a captain in the Alabama National Guard in 1903. He was reelected and commissioned in 1906, but resigned the command in 1907. City solicitor of Gadsden in 1911–1917.
Rainey was elected as a Democrat to the Sixty-sixth Congress to fill the vacancy caused by the death of John L. Burnett. He was reelected to the Sixty-seventh Congress and served from September 30, 1919, to March 3, 1923. He declined to be a candidate for renomination in 1922. Trustee of the State department of archives and history, Montgomery, Alabama. He resumed the practice of law in Gadsden, Alabama, until his death there September 27, 1959. He was interred in Glenwood Cemetery, Fort Payne, Alabama.