Michèle Angélique Flournoy (born December 14, 1960) is an American defense policy expert renowned for her roles in high-level national security positions. She served as Under Secretary of Defense for Policy from 2009 to 2012 under President Barack Obama, acting as the principal advisor to the Secretary of Defense on the formulation of national security and defense policy, oversight of military plans and operations, and participation in National Security Council deliberations. Prior to this, under President Bill Clinton, she held the position of Deputy Assistant Secretary of Defense for Strategy, contributing significantly to U.S. defense strategy during the 1990s. Flournoy is also a co-founder of WestExec Advisors, where she serves as Managing Partner, providing strategic consulting on defense and foreign policy issues.

In addition to her government service, Flournoy co-founded the Center for a New American Security (CNAS) and previously served as its Chief Executive Officer, now acting as Chair of the Board of Directors. She holds influential board positions at organizations such as Booz Allen Hamilton, Astra, Amida Technology Solutions, America’s Frontier Fund, The Gates Global Policy Center, The Mission Continues, The War Horse, and CARE. Flournoy also serves on advisory boards for entities including the Council on Foreign Relations and Spirit of America, extending her influence across think tanks, corporations, and non-profits focused on national security and global policy.

Flournoy's academic background includes a bachelor’s degree in social studies from Harvard University and a master’s degree in international relations from Balliol College, Oxford University, where she was a Newton-Tatum scholar. Her career bridges government, business, and non-governmental sectors, positioning her as a key figure in shaping U.S. defense policy and international relations.