Masasue Suō (周防 正季, Suō Masasue, October 8, 1885 – June 20, 1942) was a Japanese physician, the director of the Sorok Island Sanatorium in Korea. He completed the world's biggest leprosy facility Sorok Island Sanatorium hospitalizing 6000 patients. He was assassinated by a patient while rushing to a morning ceremony. Forced segregation of leprosy patients, inhumane treatments towards patients, and antipathy against colonial rule were behind the assassination.