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

Pierre Paul Émile Roux FRS 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.

The Pasteur Institute is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who invented pasteurization and vaccines for anthrax and rabies. The institute was founded on 4 June 1887 and inaugurated on 14 November 1888.