XoXaan is a humanoid female who (along with eleven other Jedi defectors) became the first Lords of the Sith.
As Marchioness of the Dark Jedi's Black Legions, XoXaan fought in the cataclysmic Hundred-Year Darkness war only to be defeated and exiled from the Jedi Order following a rout on the world of Corbos.
Guilty of high treason, XoXaan was among the beaten Dark Jedi that were banished from the Republic, only to discover Korriban, where they found and enslaved the aboriginal Sith species. Christened as the first of the Sith Lords, XoXaan and her contemporaries instituted a religion that centered around worship and practice of the dark side of the Force.
Though other Sith Lords possessed similar talents, XoXaan was noted amongst her peers for her skills in dark side healing. She recorded her knowledge in a holocron, which was entombed with her in Korriban's Valley of the Dark Lords. Her spirit waited thousands of years for someone to come along whom she felt was worthy of her Sith teachings, and found one such student in the ex-Jedi A'Sharad Hett.
From Xoxaan's spirit and holocron, Hett learned the ways of the dark side, and eventually created a new Sith Order based on her teachings. After Hett assumed the mantle of Dark Lord of the Sith under the moniker Darth Krayt, he constructed a massive statue in reverence of XoXaan — who was considered his first and greatest Sith teacher — within the Temple of the Sith on the planet Coruscant.