William Alexander Hammond (28 August 1828 – 5 January 1900) was an American military physician and neurologist. During the American Civil War he was the eleventh Surgeon General of the United States Army (1862–1864) and the founder of the Army Medical Museum (now the National Museum of Health and Medicine). He was the first American physician to devote himself entirely to neurology, the author of the first American treatise about neurology, and one of the founders of the American Neurological Association.