John Harnad (born Hernád János) is a Hungarian-born Canadian mathematical physicist. He did his undergraduate studies at McGill University and his doctorate at the University of Oxford (D.Phil. 1972) under the supervision of John C. Taylor. His research is on integrable systems, gauge theory and random matrices. In 2006, he was recipient of the CAP-CRM Prize in Theoretical and Mathematical Physics "For his deep and lasting contributions to the theory of integrable systems with connections to gauge theory, inverse scattering and random matrices".