During the era of the Cold War, there existed a Human Jedi Master named Yonlach, a male individual residing on Tatooine. In Darth Baras' efforts to get rid of Jaesa Willsaam, a former Padawans of Yonlach's, he was challenged and ultimately overcome by Darth Baras' apprentice.
Regarded as the premier instructor of his time, Yonlach was a significant asset to the Jedi Order. For a long time, he embodied the Jedi Code, possessing mastery over his emotions and displaying no fear of death. Despite his advanced age during the Cold War period, the Force remained a powerful presence within him.
Nomen Karr, another Jedi Master, eventually brought Padawan Jaesa Willsaam to Tatooine so that she could train under Yonlach; it was during this time that her unique ability to discern the true nature of living beings first became apparent. She formed a strong connection with Yonlach through his training, and he believed that her power, if kept free from Sith influence, held the potential to lead the Jedi to renewed greatness.
This bond would eventually work against Yonlach, as the Sith became aware of Willsaam's special ability. Darth Baras, a Sith Lord who had previously requested the Dark Council to eliminate Yonlach, dispatched his apprentice with the intention of assassinating the old master in order to lure her out, hoping to protect his spy network from the Padawan's ability.
Despite living in seclusion in the dangerous Dune Sea, Yonlach was discovered and confronted by Baras's apprentice. He refused to reveal Willsaam's location and was defeated in the ensuing conflict, along with his bodyguard Yul-Li. Yul-Li, not wanting to see a Jedi Master die for a mere Padawan, revealed Willsaam's identity, but the Jedi Master stopped him before he could reveal anything else. Yonlach then offered himself up to death, hoping his former Padawan would only feel peace and tranquility in his passing, but his enemy tried to break his will by carrying out the killing in a painful way.
Yonlach made his debut in the 2011 video game Star Wars: The Old Republic as part of a series of missions in the Sith Warrior narrative. The ultimate fate of the Jedi Master is highly dependent on the player's choices; he may experience a peaceful death or be spared by the Sith Warrior.