Pierre Paul Émile Roux FRS (17 December 1853, Confolens, Charente – 3 November 1933, Paris) was a French physician, bacteriologist and immunologist.
Roux was one of the closest collaborators of Louis Pasteur (1822–1895), a co-founder of the Pasteur Institute, and responsible for the Institute's production of the anti-diphtheria serum, the first effective therapy for this disease.