Philippe G. Ciarlet (born October 14, 1938, Paris) is a French mathematician, known particularly for his work on mathematical analysis of the finite element method especially applied to elasticity. He has contributed also to analysis of partial differential equations and differential geometry.
Alumnus of the École polytechnique and École Nationale des Ponts et Chaussées in Paris, Ciarlet earned a Ph.D. from Case Institute of Technology in Cleveland, Ohio in 1966 for a thesis entitled Variational Methods for Non-Linear Boundary-Value Problems under Richard S. Varga.
Returning to Paris, Ciarlet was awarded a higher doctorate under the supervision of Jacques-Louis Lions. From 1974 to 2002, Ciarlet held the post of Professor at the Pierre and Marie Curie University, Paris. He currently holds a chair in the Department of Mathematics at the City University of Hong Kong.
Ciarlet has been awarded the Grand Prize (Prix Jaffé) of the French Academy of Sciences in 1989, membership of the French Academy of Sciences and the Légion d'honneur, both in 1999. He is a member of the Academies of Science of several other countries. In 2012 he became a fellow of the American Mathematical Society.