Mazhar Osman Usman (born 5 May 1884, Soufli[1] - 31 August 1951, Istanbul) was a Turkish psychiatrist and neurologist which founded the first modern psychiatric hospital in Turkey.
In Munich he studied with Alzheimer and Kraepelin, the most important names of modern psychiatry, and in Berlin with Ziehen.
The process, which started in 1924 with the approval of then President Mustafa Kemal Atatürk, Prime Minister İsmet İnönü and Minister of Interior Refik Saydam, was completed with the establishment of Bakırköy Mental and Nervous Diseases Hospital on June 15, 1927.
In 1941, he left his position as Chief Physician and continued to work as a faculty member until 1951, when he retired.
He played an important role in establishing serology, neuro-pathology and experimental psychology laboratories for the first time in Turkey.