Ḥasan (Ḥusayn, Ḥassūn) ben Mashiaḥ was a tenth-century Karaite scholar who probably lived in Baghdad. According to Ibn al-Hītī, he disputed with the Christian scholar-physician Abū ʿAlī ʿIsā ibn Zurʿa (d. 1009), the author of a polemical work against the Jews entitled Epistle to Ibn Shuʿayb. He also wrote refutations of Saʿadya Gaon. Although it is unlikely from a chronological standpoint, Ibn al-Hītī states in his chronicle that Ḥasan ben Mashiaḥ was a contemporary of Salmon ben Jeroham and Saʿadya Gaon, and Sahl ben Maṣliaḥ even asserts that he had a verbal disputation with t…