Wilder Penfield can be called, without exaggeration, one of the great medical minds in Canadian history. He was one of Canada’s foremost neurosurgeons, and his research made major breakthroughs in the understanding and treatment of various forms of epilepsy and of brain scars resulting from trauma. Penfield is also known for creating maps of the sensory and motor sections of the brain, showing their connections to the various limbs and organs of the body, that are still used today. And the scientific papers, handbooks and monographs he wrote with associates became that standard reference works on the function of the human brain. Penfield’s most lasting legacy was the establishment of the Montreal Neurological Institute in 1934, where he served as director until 1960. The Montreal Neurological Institute and Hospital continues to provide a world-renowned centre for students and physicians to study the brain. It has also served as a model for similar hospitals throughout the world. Finally, Penfield devoted himself to public service, particularly in support of university education. He became widely known as well for promoting early second-language training. In 1967, Dr. Penfield was made a Companion of the Order of Canada. In 1994, he was inducted into the Canadian Medical Hall of Fame. He is the Greatest McGillian because he is a pivotal figure in our understanding of a very fundamental part of us, the human brain.