Hai Gaon (969-1038) was one of the last "geonim" (rabbinic authorities of the early Middle Ages). He was the head of the academy at Pumbedita, Babylonia. He authored both a commentary on the Talmud as well as a collection of responsa, plus several other smaller works on focused topics. His father, Rav Sherira Gaon, was his teacher and predecessor as head of the academy. His students included Rabbeinu Chananel and Rav Nissim, the head of the academy at Kairouan. Wikipedia
Rav Rabba (Mar Aba Gaon). (Alternatively according to David HUGHES RDavidH218@aol.com Mar Rav Aba was the son of Sofro Demar Yosef son of Rabba Gaon son of Dodai Gaon son of Nachma son of Ravya.) www.loebtree.com/kings.html#hai
The definitive Wikipedia entry for Hai Gaon. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Hai_Gaon
