Ōishi Yoshio (大石 良雄, 24 April 1659 – 20 March 1703) was the chamberlain (karō) of the Akō Domain in Harima Province (now Hyōgo Prefecture), Japan (1679 - 1701). He is known as the leader of the Forty-seven Rōnin in their 1702 vendetta and thus the hero of the Chūshingura. He is often referred to by his title, Ōishi Kuranosuke (大石内蔵助).