Alexandre Emile Jean Yersin (September 22; 1863-March 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 詎g Nam (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閑 has his name. A private university founded in 2004 in Da Lat was named 'Yersin University' in his honour.