Louis Jean Odier (March 17, 1748 – April 14, 1817, Geneva) was a Genevan and then Swiss physician, medical campaigner and advisor; he was also a translator and publisher of medical texts, particularly from English. He was a major figure in medicine in 18th-century Europe because of his promotion of vaccination against smallpox and more broadly his lobbying for medical funds and usage of data from historical medical records, relating them to probability in life expectancy and subsequent advice for economic planning.