Natronai ben Hilai (Hebrew: נטרונאי בן הלאי) was Gaon of the academy at Sura early in the second half of the 9th century; he succeeded Sar Shalom. His father had occupied the position about thirty years before. Although Naṭronai was of advanced age when he entered on the office, and although his official term embraced less than a decade, an unusually large number of responsa were issued by him. Questions were addressed to him from all parts of the Jewish Diaspora; and his answers, about 300 of which have been preserved in various compilations (e.g., in Sha'are Ẓedeḳ, Teshubot ha-Ge'onim, and Ḳebuẓat ha-Ḥakamim), show his thorough mastery of the subjects treated as well as his ability to impart knowledge. He always employed the language with which his correspondents were most conversant. Wi