Madelyn Creedon is a Research Professor of International Affairs and Chair of the Nuclear Security Working Group at the George Washington University. She has had a long and distinguished career in U.S. government service, most recently as Principal Deputy Administrator of the National Nuclear Security Administration (NNSA) within the Department of Energy, a position she held from 2014 to 2017. She also served in the Pentagon as Assistant Secretary of Defense for Global Strategic Affairs from 2011 to 2014, overseeing policy development in the areas of missile defense, nuclear security, cybersecurity, and space. She served as counsel for the U.S. Senate Committee on Armed Services for many years, beginning in 1990; assignments and focus areas included the Subcommittee on Strategic Forces as well as threat reduction and nuclear nonproliferation. During that time, she also served as Deputy Administrator for Defense Programs at the NNSA, Associate Deputy Secretary of Energy, and General Counsel for the Defense Base Closure and Realignment Commission. She started her career as a trial attorney at the Department of Energy. Following retirement from Federal Service in 2017, Madelyn established Green Marble Group, LLC, a consulting company and currently serves on a number of advisory boards related to national security. She recently completed a fellowship at the United States Study Center at the University of Sydney and is currently a non-resident senior at The Brookings Institution. She holds a J.D. from St. Louis University School of Law, and a B.A. from the University of Evansville.