James Paul Warburg (August 18, 1896 – June 3, 1969) was a German-born American banker. He was well known for being the financial adviser to Franklin D. Roosevelt. His father was banker Paul Warburg, member of the Warburg family and "father" of the Federal Reserve system. After World War II, Warburg helped organized the Society for the Prevention of World War III in support of the Morgenthau Plan.