Barry Gordon Buzan (born 28 April 1946) is Emeritus Professor of International Relations at the London School of Economics and honorary professor at the University of Copenhagen and Jilin University. Until 2012 he was Montague Burton Professor of International Relations at the LSE. Buzan sketched the Regional Security Complex Theory and is therefore together with Ole Wæver a central figure of the Copenhagen School. From 1988 to 2002 he was Project Director at the Copenhagen Peace Research Institute (COPRI). From 1995 to 2002 he was research Professor of International Studies at the University of Westminster. He was Chairman of the British International Studies Association 1988-90, Vice-President of the (North American) International Studies Association 1993-4, and founding Secretary of the International Studies Coordinating Committee 1994-8. From 1999 to 2011 he was the general coordinator of a project to reconvene the English school of International Relations, and from 2004-8 he was editor of the European Journal of International Relations. In 1998 he was elected a fellow of the British Academy, and in 2001 he was elected as an Academician of the Association of Learned Societies in the Social Sciences.

His main research areas are the conceptual and regional aspects of international security; international history, and the evolution of the international system since prehistory; international relations theory, particularly structural realism; international society, and the 'English School' approach to International Relations. His books includes Regions and Powers: The Structure of International Security (2003, with Ole Waever), The Evolution of International Security Studies (2009, with Lene Hansen), and Non-Western International Relations Theory: Perspectives on and beyond Asia (2010).