Stathis N. Kalyvas (Greek: Στάθης Ν. Καλύβας; born 7 March 1964) is a Greek political scientist who is the Gladstone Professor of Government, at the University of Oxford and a University Academic Fellow at All Souls College, Oxford.

Kalyvas held the Arnold Wolfers Chair in Political Science at Yale University (from 2003 to 2017), where he founded the Program on Order, Conflict, and Violence; prior to that,he held professorships at the University of Chicago, New York University, and Ohio State University. He has also conducted research at the Peace Research Institute Oslo. Kalyvas has written extensively on civil wars, ethnicity, and political violence.

He was a main founder, with Nikos Marantzides, of a current in Modern Greek historiography called the "New Wave" which was focused principally on the study of the Greek Civil War. Among his works is The Logic of Violence in Civil War, which challenges the view of violence in civil wars as irrational.

Kalyvas was born on the island Corfu (Kerkyra) in 1964, where his father was serving in the Hellenic Coast Guard at the time. His family later moved to Athens and it was there that he spent his early childhood; residing first in Kolonos, and later in Nea Smyrni. His mother was French, and at the age of ten, the family moved to Marseille, where he spent his adolescent years and completed his general education.

Kalyvas completed his undergraduate studies at the National and Kapodistrian University of Athens in 1986, and received his PhD diploma in Political Science at the University of Chicago in 1993. Besides Yale, he also taught at Ohio State University from 1993-94, NYU from 1994-2000, and the University of Chicago from 2000-2003.

He has also been a visiting professor or scholar at Northwestern University, Columbia University, Witten/Herdecke University, Instituto Carlos III-Juan March, the Max Planck Institute, and European University. He has written, amongst other works, The Logic of Violence in Civil War (Cambridge University Press, 2006) and The Rise of Christian Democracy in Europe (Cornell University Press, 1996). He is a contributor and editor to the book Order, Conflict, and Violence (Cambridge University Press, 2008), and more than fifty scholarly articles in five languages.

He has been a frequent contributor to the newspaper Kathimerini since 2009. His articles and have been published in multiple mass-media outlets, such as the New York Times, Financial Times, Foreign Affairs, Foreign Policy, and The Atlantic.

He has been a member of the Konstantinos Karamanlis Institute for Democracy, a think tank affiliated with the New Democracy party.