Barbara Cassin (French: [kasɛ̃]; born 24 October 1947, Boulogne-Billancourt) is a French philologist and philosopher.
A past director at Jacques Derrida's Collège international de philosophie and director of research (senior research chair) at the CNRS. In 2006 she succeeded Jonathan Barnes to the directorship of the leading centre of excellence in Ancient philosophy, Centre Leon-Robin, at the Sorbonne.
Her work centers on Sophism and rhetoric, and their relation to philosophy. In a footnote in 2007's Logic of Worlds, Alain Badiou portrays her work as a synthesis of Heideggerian thought with the linguistic turn.
From 1991 to 2007, she co-directed with Alain Badiou the series L'Ordre Philosophique, at Le Seuil publishers.
She is the author of L'Effet Sophistique (1995) and the editor of Vocabulaire Européen des Philosophies, ( 2004) an international collective work of philosophers sponsored by the European Union. She has also written Google-moi. La Deuxième Mission de l'Amérique (2007),
In September 2012, a Cerisy symposium about her works was held, with contributions by Étienne Balibar, Fernando Santoro, Michel Deguy, Souleymane Bachir Diagne, Philippe-Joseph Salazar and Alain Badiou, among others.