Joseph Berry Keenan (11 January 1888, in Pawtucket, Rhode Island – 8 December 1954, in Asheboro, North Carolina) was a United States political figure. He served in the administrations of Franklin Roosevelt and Harry Truman, and was the chief prosecutor in the International Military Tribunal for the Far East.
He graduated from Brown University in 1910 and earned his Juris Doctor at Harvard Law School. Keenan served with the 137th Field Artillery during World War I and later with the Judge Advocate Generals Department. After retiring from military, he became an assistant to the U.S. attorney general and director of the Criminal Division of the Justice Department. During his tenure, he was responsible for the prosecution of "Machine Gun Kelly" and the "Ma Barker Gang".