Walter Emanuel Treanor (November 17, 1883 – April 26, 1941) was a United States federal judge.
Born in Loogootee, Indiana, Treanor received an A.B. from Indiana University in 1912 and an LL.B. from Indiana University School of Law in 1922. He was in the United States Army Second Lieutenant during World War I, from 1917 to 1919. He was a Professor of law, Indiana University Law School from 1922 to 1930. He was a judge on the Indiana Supreme Court from 1930 to 1936.
Treanor was a federal judge on the United States Court of Appeals for the Seventh Circuit. Treanor was nominated by President Franklin D. Roosevelt on December 11, 1937, to a seat vacated by Samuel Alschuler. He was confirmed by the United States Senate on December 21, 1937, and received his commission on December 27, 1937. Treanor served in that capacity until April 26, 1941, due to his death.