Wilder Graves Penfield OM CC CMG FRS (January 26, 1891 – April 5, 1976) was a pioneering neurosurgeon once dubbed "the greatest living Canadian". He expanded brain surgery's methods and techniques, including mapping the functions of various regions of the brain such as the cortical homunculus. His scientific contributions on neural stimulation expand across a variety of topics including hallucinations, illusions, and deja vu.