Eldrak Korsin, a Human male, was an experienced space admiral who served in the navy of the Sith Empire in the years prior to the Great Hyperspace War. Korsin came from a family descended from Tapani nobles, who at some point became subjects of the Sith. The Korsin clan became valuable to their new masters, working in commerce and industry, and interbreeding with the Empire's Dark Jedi. As a result, Korsin was Force-sensitive, and he went on to become a highly respected spacer, never losing a ship in his long career. During his naval career, he served alongside his trusted helmsman, Boyle Marcom. He married a woman named Takara, and with her had a son, Yaru, who learned the trade at his father's side.
Unbeknownst to Korsin, he had another son, Devore—born to a woman on a planet somewhere. Devore eventually sought out his father, and the Admiral embraced him without a second thought. The revelation encouraged Yaru to pursue a naval career more aggressively, and he rose through the ranks to captain. Yaru's first command was of a newly-christened Sith dreadnaught named the Omen, winning control of the ship over Admiral Korsin himself. Although he had never lost a ship for the Sith Lords, he had lost one to his son, an occurrence that irked Korsin. As for Devore, a spice addiction derailed his prospective naval career, so Korsin sponsored his efforts to become a member of the Sith mineralogical corps. In 5000 BBY, Yaru and Devore, on a Lignan mining expedition, disappeared along with the Omen and Korsin's old helmsman, Marcom. In reality, they crash-landed on an uncharted world known as Kesh, where the Omens surviving crew went on to form a Sith tribe. Korsin's grandchildren: his grandson, Jariad, and granddaughter, Nida, would be raised on Kesh.
Korsin was an extremely reliable admiral for the Sith, never losing a ship during his entire career. Possessed of a ruddy and squat frame, which he passed on to his son Yaru, Korsin was very supportive of his children's pursuits, sponsoring Yaru's naval ambitions and Devore's efforts to break into the Sith mineralogical corps. Furthermore, he accepted Devore without a second thought, even after not knowing of his son's existence. However, he still held a fair amount of pride and disliked losing command of the Omen to Yaru.
Korsin was first mentioned in Lost Tribe of the Sith: Precipice, a 2009 eBook written by John Jackson Miller. Although Korsin's first name is not given in the original edition of Precipice, he is identified as Eldrak Korsin in the version of Precipice included in the 2012 compilation Star Wars: Lost Tribe of the Sith: The Collected Stories.