Stuart Eizenstat (born January 15, 1943) is an American diplomat and attorney. He served as the United States Ambassador to the European Union from 1993 to 1996 and as the United States Deputy Secretary of the Treasury from 1999 to 2001. He currently serves as a partner at the Washington, D.C.-based law firm Covington & Burling and as a senior strategist at APCO Worldwide.