Louis - Antoine Ranvier (2 October 1835 – 22 March 1922) was a French physician, pathologist, anatomist and histologist, who discovered nodes of Ranvier, regularly spaced constrictions of the myelin sheath, occurring at varying intervals along the length of a nerve fiber.

Ranvier was born and studied medicine at Lyon, graduating in 1865. He founded a small private research laboratory with Victor André Cornil, and together they offered a course in histology to medical students. They also wrote together an influential textbook on histopathology. In 1867, Ranvier entered the Collège de France and worked as an assistant to Claude Bernard. In 1875, he was appointed to its chair of general anatomy.

In 1878, Ranvier discovered the nodes which received his name. Other anatomical structures bearing his name are the Merkel - Ranvier cells, melanocyte - like cells in the basal layer of the epidermis that contain catecholamine granules; and Ranvier's tactile disks, a special type of sensory nerve ending. In 1897, he founded the scientific journal Archives d'anatomie microscopique with Edouard - Gérard Balbiani.

Some of his most noted students were Ferdinand - Jean Darier, Justin Marie Jolly, Joaquín Albarrán, Luis Simarro Lacabra and Fredrik Georg Gade.

He retired in 1900 to his estate in Thélys (Roanne) and died at Vendranges in 1922.