Hai ben Sherira (or Hai b. Sherira (Gaon), Hebrew: האי בר שרירא; better known as Hai Gaon, Hebrew: האיי גאון, b. 939, d. March 28, 1038), was a medieval Jewish theologian, rabbi and scholar who served as Gaon of the Talmudic academy of Pumbedita during the early 11th century. He received his Talmudic education from his father, Sherira ben Hanina, and in early life acted as his assistant in teaching. In his forty-fourth year he became associated with his father as "ab bet din," and with him delivered many joint decisions.