James Martin Barnes (January 9, 1899 – June 8, 1958) was a member of the U.S. House of Representatives from Illinois and administrative assistant to Presidents Franklin D. Roosevelt and Harry S. Truman.

He attended the local schools and served in the United States Marine Corps during World War I.

[2] A Democrat, he served as Morgan County Judge from 1926 to 1934, afterwards resuming the practice of law.

He continued in the position under President Truman following Roosevelt's death, serving from March 1, 1943, to July 15, 1945.

[11] This article incorporates public domain material from the Biographical Directory of the United States Congress