William Lockhart "Will" Clayton was an American business leader and government official. Much of his business career centered on cotton trading. He and his three brothers-in-law formed a partnership that grew into the Anderson, Clayton and Company, at one time the world's largest cotton trading company. Politically aligned with the Democratic Party, he opposed some of President Franklin D. Roosevelt's agricultural policies. He repudiated his opposition after Roosevelt's Secretary of State Cordell Hull worked for a reciprocal trade agreement.
Returning to government service in 1940, Clayton first Later in World War II, he took on a number of roles in the Roosevelt and Truman administrations. He first served as deputy to the coordinator of inter-American affairs. For the next four years he held a variety of high-level positions with the Export-Import Bank, the Department of Commerce, and wartime agencies. He served as assistant, and then as deputy Secretary of State for economic affairs from December 1944 to October 1947, where he was primarily concerned with working on the Marshall Plan.