Tenebrae (Darth Vitiate)

Born in 5113 BBY as the illegitimate Sith son of Lord Dramath in the Old Sith Empire, Tenebrae carved a path of destruction across the planet Medriaas, torturing and massacring thousands by the age of ten. When Dramath confronted him, Tenebrae severed his father's power and imprisoned his spirit for millennia of torment. Eventually, the Dark Lord of the Sith Marka Ragnos recognized Tenebrae's power and christened him as Lord Vitiate—the new ruler of Medriaas. Vitiate renamed the world Nathema and ruled it for the next century, distancing himself from Sith power struggles. Following Naga Sadow's defeat in the Great Hyperspace War, Vitiate lured the remaining Sith Lords to Nathema and, in an elaborate ritual, drained their life essence and that of the entire planet, increasing his powers and prolonging his life.

Shedding his identity as Lord Vitiate, the self-proclaimed Sith Emperor led the scattered Sith survivors to Dromund Kaas and established a new Sith Empire. As the Empire secretly expanded over the next thousand years, the Emperor discovered the lost world of Zakuul and the Eternal Fleet—an ancient armada with unmatched technology. Dissatisfied with Sith ideology, the Emperor divided his consciousness into a Zakuulan warrior named Valkorion and created a vast civilization known as the Eternal Empire. The Emperor desired absolute immortality to experience and expand his new creation across galaxies, so he plotted to initiate a war between his Sith Empire and the Galactic Republic. The deaths caused by the conflict would fuel a new ritual that would allow him to consume almost everything in the galaxy and become an all-powerful god.

As the Emperor's plans neared completion, he orchestrated the Mandalorian Wars as a preliminary invasion of the Republic, but two powerful Jedi Knights—Revan and Malak—defeated the Mandalorians and tracked down his Sith Empire. The Emperor dominated their minds, but the pair soon broke free from his control and betrayed him—and each other—in the resultant Jedi Civil War that nearly destroyed the Jedi Order. A redeemed Revan waged a mental war against the Emperor, delaying his Great Galactic War by three centuries. The Sith Empire still nearly conquered the Republic, but Revan further influenced Vitiate—distracted by the births of his three children to the Zakuul Knight Senya Tirall—to sue for peace instead, prompting a decade-long Treaty of Coruscant.

As hostilities resumed, Dark Councillor Darth Baras lured the Emperor to the planet Voss, trapping him in the domain of the dark side entity Sel-Makor until he was rescued by the second Emperor's Wrath. Freed, the Emperor attempted to initiate his galaxy-wide ritual, but a powerful Jedi Knight known as the Hero of Tython thwarted his efforts and destroyed his host body in battle on Dromund Kaas. His wounded spirit went into slumber on Yavin IV until a returned and crazed Revan attempted to resurrect the weakened Emperor to a physical form to permanently destroy him. Although Revan's plans were foiled, the Emperor's spirit fed off the battle and reawakened, then struck against his former Sith Empire and consumed the planet Ziost to return to full power.

Reassuming the visage of Valkorion, he revealed the Eternal Empire to the galaxy as his twin sons—Arcann and Thexan—invaded Imperial and Republic space and captured a famous champion later known as the Outlander. Judging the Outlander alone to be a worthy adversary, Valkorion orchestrated his death at the hands of Arcann and embedded his consciousness within the Outlander's mind. Valkorion counseled and shaped the Outlander into a vessel of supreme power as the champion defeated Arcann, then his daughter Vaylin, and disabled the Eternal Fleet. Valkorion sought to take over the champion's body and rule the galaxy as a heroic liberator but, in a final clash of wills, the Outlander and Valkorion's own family banished the ancient entity into the void.