This article is about the English surgeon; for other people named William Little see William Little (disambiguation).

William John Little (1810–1894) was an English surgeon who is credited with the first medical identification of spastic diplegia, when he observed it in the 1860s amongst children. While spasticity surely existed before that point, Little was the first person to medically record the condition in writing. Thus, for many years, spastic diplegia was known as Little's Disease; only later did the name change. Also, Little founded the Royal Orthopaedic Hospital of London.