Gustave Roussy (French pronunciation: [ɡystav ʁusi]; 24 November 1874 – 30 September 1948) was a Swiss-French neuropathologist born in Vevey, Switzerland.
As a hospital interne in Paris, Roussy worked under neurologists Pierre Marie and Joseph Jules Dejerine.
Roussy made several contributions in the field of neurology, in particular, his investigations on the role of the thalamus and the autonomic nervous system.
During World War I he was chief of neurology of the 7th Military Region Besançon, publishing extensively on his experiences with battle-related wounds.
In 1926, in collaboration with his colleague Gabrielle Charlotte Lévy, he published an article describing seven patients with hereditary areflexive dystasia, which then became known as Roussy-Lévy syndrome.