Antoine Louis (February 13, 1723 – May 20, 1792) was a French surgeon and physiologist who was born in Metz.
He was originally trained in medicine by his father, a surgeon-major at a local military hospital. As a young man he moved to Paris, where he served as gagnant-maîtrise at the Salpêtrière. In 1750 he was appointed professor of physiology, a position he maintained for forty years. In 1764 he was appointed lifetime secretary to the Académie Royale de Chirurgie.
Louis published numerous articles on surgery, including several biographies of surgeons who died during his lifetime. He also published the surgical aphorisms of Dutch physician Hermann Boerhaave (1668–1738).
Louis is credited with designing a prototype of the guillotine. This device however, is named after French physician Joseph Ignace Guillotin (1738–1814), who was an advocate of a more humane method of capital punishment. For a period of time after its invention, the guillotine was called a louisette.
Another name for the sternal angle is the "angle of Louis", which is the point of junction between the manubrium and the body of the sternum.