Eulyn, a Keshiri woman, resided on the world of Kesh circa 5000 BBY. She was the mother to Adari Vaal, a widowed geologist, and she took care of her two grandchildren, Tona and Finn. They lived in a wood dwelling in the urban center of Tahv, a place she inherited following the passing of her son-in-law, Zhari Vaal. Adari gained notoriety for teachings that went against the established faith of that era, leading Eulyn to consider her daughter a heretic. After an irate crowd bombarded their home with stones, Adari ran away and happened upon a group of Sith who declared themselves to be divine beings. While Adari was celebrated for her role, Eulyn never grasped her daughter's sainthood and passed away sometime before 4975 BBY.
Eulyn, a Keshiri female, was born on the planet Kesh and lived during the Great Hyperspace War. She was the parent of Adari, a geologist that married Zhari Vaal, a member of the ruling Neshtovar family. Eulyn played a major role in orchestrating the marriage; she spent years advocating for the union, hoping to strengthen her family's standing. Following Vaal's demise in an uvak accident, Eulyn and Adari inherited a wooden residence in the city of Tahv, where Eulyn cared for her grandchildren, Tona and Finn. Adari's geological work revealed information about the Keshiri landscape's formation that contradicted the popular religious belief that the Skyborn gods created the planet's continents with their blood. She began sharing these findings, and Eulyn, an ardent believer in the Skyborn religion who generally disapproved of her daughter's profession, considered her a heretic and was horrified by her discoveries.
In 5000 BBY, Adari testified to the Neshtovar about her findings, resulting in angry mobs attacking Eulyn and Adari's home with rocks. The barrage became so intense that Adari sent Eulyn and the children to stay with her uncle. Adari fled the enraged Keshiri on her late husband's uvak, Nink, and discovered a Sith crash site in the high Cetajan Mountains. She found a group of surviving Sith, led by Captain Yaru Korsin, and guided them back to civilization. The Sith proclaimed themselves to be the Skyborn, and Adari was celebrated for her actions. Eulyn, who had not understood her daughter's supposed heresy, also failed to understand her canonization, and she died before 4975 BBY. After her passing, Adari's personal memoirs, written during her exile in the distant continent of Alanciar, were discovered and contained critical remarks about Eulyn.
Eulyn was a dedicated follower of the Skyborn religion and was therefore disgusted by what she saw as her daughter's heresy. Eulyn struggled to understand Adari's commitment to her theories, her profession, and her veneration following the Sith's arrival, and she often argued with her. She was very ambitious for her family, lobbying extensively for Adari to marry a powerful Neshtovar member, and she was thrilled when she acquired a high-end wooden house. Eulyn had violet skin and dark eyes.
Eulyn's first appearance was in Lost Tribe of the Sith: Skyborn, a 2009 digital book by John Jackson Miller.