Answer
The answer is Franklin D. Roosevelt. He appointed James Francis Byrnes to the Supreme Court in June 1941, filling the vacancy left by the death of James Clark McReynolds. Byrnes served as an associate justice until 1942 when he resigned to become Director of Economic Stabilization. He later served as Secretary of State from 1945 to 1947 and as Governor of South Carolina from 1951 to 1955.