Koro Ziil Koro Ziil , also known as the Hidden One and hu ' aac - du ' ul - staranjan — which , translated from his native language to Basic , meant " " the one who dwells in darkness " " — was a male Force - sensitive Kel Dor . He was a member of the Baran Do Sages , a group of Force - sensitive Kel Dor on the planet Dorin . He was one of the few Baran Do to be trained in combat , and became the Master of the Order . Ziil trained Baran Do Sage Charsae Saal , who would become the senior combat instructor at the Baran Do temple . In 34 ABY , Ziil also taught many Baran Do Force techniques to Jedi Knight Jacen Solo , who had spent the last five years traveling the galaxy learning among other Force - based organizations . By 43 . 5 ABY , Ziil had become the leader of the Hidden Ones — a secret sect of the Baran Do tasked with preserving the Order ' s knowledge . The Hidden Ones lived in a series of caverns deep below the surface of Dorin , where they could remain hidden from the rest of the galaxy . In 43 . 5 ABY , Ziil met with Jedi Grand Master Luke Skywalker — who had been recently exiled for failing to prevent Jacen Solo ' s fall to the dark side of the Force and transformation into Darth Caedus — and Luke ' s son , Jedi Knight Ben Skywalker , shortly after becoming the leader of the Hidden Ones . Ziil attempted to coerce the Skywalkers into joining the sect , and refused to let them leave , in order to protect the sect ' s secrecy . The Skywalkers resisted , and turned many of the Hidden Ones against him . With the tension mounting between them , Ziil eventually confronted Luke in a duel , which Ziil lost . Ben then revealed the lies which Ziil had told to his sect , and the Hidden Ones revolted against his rule and returned to the surface . Biography . Becoming the Hidden One . Koro Ziil was a Force - sensitive male Kel Dor from the planet Dorin , and a member of the Baran Do Sages , a Force - based organization on Dorin . As a master of the Baran Do , he trained the Sage Charsae Saal as his apprentice . In approximately 23 ABY , he took Saal — whom he had sworn to secrecy — to the Caverns of the Hidden One , a series of caves deep beneath the surface of Dorin . Ziil believed it was likely that Saal would someday join the Hidden Ones , a secret sect of the Baran Do dedicated to preserving the knowledge of the Order , so that if the sages were ever eliminated , they would have the ability to restore their Order . Ziil went on to become Master of the Order , and was present in the Baran Do temple in Dor ' shan in 34 ABY when the Jedi Knight Jacen Solo arrived on Dorin , seeking to learn various Force techniques . Ziil taught Solo several Baran Do abilities , including " ayna - seff " , the " dead brain " technique , which took Solo three days to master , and other techniques in the " hassat - durr " family — a skill set which consisted of suffusing the wielder ' s body with a low level of electromagnetic radiation . Ziil also trained with Solo in combat . From his time with the Jedi Knight , Ziil perceived that Solo ' s childhood had been unsettled , and that the Human had severed himself from it . He also found , however , that Solo seemed to be at peace with himself and the galaxy , and that his journey for knowledge was nearing its end . Several years after leaving Dorin , Solo was trained in the ways of the dark side of the Force by the Dark Lady of the Sith Lumiya . He went on to become the Sith Lord Darth Caedus , leading the Galactic Alliance in the Second Galactic Civil War . Nine years after meeting Solo , Ziil went through the ceremony of " death " — traditional to the Baran Do who wished to join the Hidden Ones . When a Baran Do sage felt that they had done everything necessary in their life , and had nothing left for which to live but the preservation of knowledge , a ritual was performed wherein they pretended to die . After this ceremony , they would join the Hidden Ones , deep beneath the surface of Dorin . Sometime after Ziil joined the Hidden Ones , he became their leader , known as " hu ' aac - du ' ul - staranjan " — which , translated into Basic , meant " " the one who dwells in darkness " " — and took on the formal title of the Hidden One , no longer recognizing his old name . Unrest in the Hidden Ones . Shortly after Ziil joined the Hidden Ones , Jedi Grand Master Luke Skywalker — who had been exiled from Coruscant and the Jedi Order by Chief of State Natasi Daala for failing to prevent Solo ' s fall to the dark side — and his son , Jedi Knight Ben Skywalker , sought out Ziil in in hopes of finding out more as to why Solo had turned to the dark side . Upon locating the Baran Do sages in Dor ' shan , they learned that Ziil was dead . The Skywalkers trained with the sages , later attending Charsae Saal ' s funeral ceremony , when he decided to " die " as well . However , the two Jedi found a secret chamber underneath Saal ' s pyre , where they found the sage very much alive . They convinced the sages to allow them to travel with Saal to the Hidden Ones . Saal — who now went by the name of Chara — showed them around the caves , revealing that Ziil had taken him there nearly twenty years earlier . Chara told the Skywalkers that in order to protect the secrecy of the Hidden Ones , they would never be allowed to leave . Ziil met with Luke and Ben and talked to them about his time with Jacen Solo , telling them of his training of the former Jedi . Changing the subject when it became clear that Ziil did not have much information on Solo ' s fall , Ben asked whether Ziil planned to kill the Jedi that would undoubtedly come searching for them . The Hidden One grew angry and began an argument with Ben , which finally ended when Ziil got up and walked away . Days later , Skywalker and his son set about the task of creating permanent quarters , spending their free time exploring the caverns . The Jedi Master decided to gather all of the Hidden Ones together by announcing that he and Ben would be having their naming ceremony ; however , he had no intention of actually doing so . Once they had all gathered in the throne chamber of the Hidden One , Ziil expressed his pleasure that the Skywalkers were finally choosing new names . Luke , however , revealed that when he had said they would be gathering for a naming ceremony , he meant that he was hoping to rename members of the Hidden Ones , not himself . He attempted to show the Hidden Ones that they were just wasting away down in the caverns . To Ziil ' s displeasure , the Jedi educated them on the nature of the Force and explained that it was the energy of life — including risk , energy , and vitality . Luke further stated that by accepting their " deaths " and joining the Hidden Ones , they had rejected these values , and were thus rejecting the Force , which was why they were weakening . As evidence , Skywalker pointed out that Ithia — who had been the best fighter in the Baran Do order before she joined the Hidden Ones — had recently lost three straight duels with Charsae Saal . Ithia had always been Saal ' s superior before she joined the sect , but was now weaker than the newer arrival . Ziil immediately attempted to terminate the meeting , but Skywalker continued trying to persuade the Hidden Ones that their way of life was wrong . Duel with Skywalker . As the Hidden One ran out of patience , Skywalker proposed a duel between Ben and Saal — the best fighter of the Hidden Ones , and by far Ben ' s superior in combat . The Hidden One was annoyed by the offer , but also somewhat intrigued , and agreed to the proposal when Luke promised that if Ben lost , he and Ben would accept their fate and stay in the caverns . The combatants were each armed with a hardwood staff , and a duel ensued , with Ben emerging as the victor . Because of this , the Hidden Ones were willing to listen to Skywalker ' s arguments ; even Saal , Ziil ' s former apprentice , was ready to believe the Jedi . But Ziil did not give up so easily . He revealed that he had sent word to the surface that there had been an accidental collapse in the caves , in which the Skywalkers had been killed . Therefore , there would be no need to send down any more oxygen - nitrogen canisters , which the Skywalkers needed to breathe while in the toxic atmosphere of Dorin . Without these canisters , they would run out of air within several days and die . Several Hidden Ones spoke out in protest , which only angered Ziil further . Ziil attacked the Jedi Master , blasting him with white Force lightning , which Luke blocked with his lightsaber . Skywalker began moving towards Ziil , who created a Force whirlwind . Luke deflected the whirlwind , and it continued around the colonnade until it hit a support column behind him , knocking it down . Ziil Force - threw his throne at Luke , which he intercepted with the fallen column . Skywalker then pushed the column along the ground towards Ziil , forcing him to jump over it . Using the distraction to his advantage , the elder Skywalker jumped up and kicked Ziil in the stomach in midair , sending him flying and ending the fight . Dissolution of the Hidden Ones . Even after his defeat at the hands of Skywalker , Ziil would not allow the Hidden Ones to leave . Ziil proposed that the sect would free their servants and appoint a board of advisers , and he would tell those on the surface that the earlier message reporting the deaths of the Skywalkers was a mistake . Ziil promised that after about a year , they would review the situation . Earlier , when he had been exploring the caverns , Ben had discovered a system of explosives that could be activated from any room , that when activated , would block off the only known exit from the caverns . Frustrated with Ziil ' s refusal to accept defeat , Ben set off the explosives with the Force . Ziil then advised that Ben had just doomed himself , because there was no other way in or out . Ben recognized that Ziil was lying , and then revealed to the Hidden Ones many of the lies that their leader had told them . Still , Ziil would not reveal the existence of a secret escape route from the caverns . At last , a very old Kel Dor , Burra , gave in , and revealed a secret turbolift chamber . The Hidden Ones finally returned to the Baran Do on the surface . Luke later speculated that Ziil would either find a new way to continue his old goal of preserving knowledge — such as by distributing the archives of the Baran Do — or would stay down in the caverns , unable to change his ways . Personality and traits . Ziil proved to be a very cautious leader ; he feared that the Baran Do would be purged in a similar manner as the Jedi in 19 BBY . As such , he was very set in his idea that the Hidden Ones ' mission of " dying " and preserving the Baran Do ' s knowledge was a just and noble goal . Ziil thought nothing was more important than this way of life — the way of the Hidden Ones — and was prepared to let the Skywalkers die in order to keep the caverns secret and their Order safe from the rest of the galaxy . He also carried about him a sense of superiority . Ziil expected other beings to listen to him and obey his every word , and was thus very distressed when the Hidden Ones began turning against him . Powers and abilities . One of the few Baran Do sages to be trained in combat , Ziil was also known to possess a wide range of Force powers , including mastery of the " hassat - durr " family of techniques . He was able conjure up a powerful Force whirlwind and possessed the ability to perceive buildups of energy on the planet , which could lead to dangerous weather storms . Ziil was also able to use a Force lightning technique , which gave off a white color . Behind the scenes . Koro Ziil was created by the established " Star Wars " author Aaron Allston to be the leader of the Hidden Ones in " " , the first novel in the " " series , released on March 24 , 2009 .