Osugi Sakae (?? ?, January 17, 1885 – September 16, 1923) was a radical Japanese anarchist.
He published numerous anarchist periodicals, helped translate western anarchist essays into Japanese for the first time, and created Japan's first Esperanto school in 1906.
He, Noe Ito, and his nephew were murdered in what became known as the Amakasu incident.