Hachirō Arita (有田 八郎, Arita Hachirō; 21 September 1884 – 4 March 1965) was a Japanese politician and diplomat who served as the Minister for Foreign Affairs for three terms. He coined the term Greater East Asia Co-Prosperity Sphere, which provided an official agenda for Imperial Japan's expansionism.
After the war, Arita was active as a leftist politician. The circumstances surrounding his second marriage and his unsuccessful 1959 run for Governor of Tokyo served as the model for the novel After the Banquet by Yukio Mishima. This led to a famous court case in which Arita successfully sued for invasion of privacy.