Alexandre Emile Jean Yersin (September 22, 1863?arch 1, 1943) was a Swiss and French physician and bacteriologist. He is remembered as the co-discoverer of the bacillus responsible for the bubonic plague or pest, which was later re-named in his honour (Yersinia pestis).

In order to practice medicine in France, Yersin applied for and obtained French nationality in 1888. Soon afterwards (1890), he left for French Indochina in Southeast Asia as a physician for the Messageries Maritimes company, on the Saigon-Manila line and then on the Saigon-Haiphong line. He participated in one of the Auguste Pavie missions.

Alexandre Yersin is well remembered in Vietnam, where he was affectionately called ?ng N?m (Mr. Nam/Fifth) by the people. Following the country's independence, streets named in his honor kept their designation, and his tomb in Suoi Dau was graced by a pagoda where rites are performed in his worship. Yersin's house in Nha Trang is now the Yersin Museum, and the epitaph on his tombstone describes him as a 'Benefactor and humanist, venerated by the Vietnamese people'. At Hanoi (Ha Noi), a French Lyc矇e has his name. A private university founded in 2004 in Da Lat was named 'Yersin University' in his honour.