Pierre Paul Émile Roux, French physician and immunologist, co-founded the Pasteur Institute (d. 1933)

Pierre Paul Émile Roux FRS (17 December 1853 – 3 November 1933) 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. Additionally, he investigated cholera, chicken-cholera, rabies, and tuberculosis. Roux is regarded as a founder of the field of immunology.