A Kilji individual, identified as "Vassal One," functioned as a Kilji vassal for the Kilji Illumine—the governing body of the Kilji species—and adhered to the Illumine's religious beliefs. In 18 BBY, this individual served on the Kilji war cruiser Anvil under the command of the Illumine's General Crofyp. Crofyp's task force, which included the Anvil and the Kilji picket cruiser Hammer, journeyed to the Unknown Regions' Rapacc system with the mission of extracting a group of refugees. However, their mission was confronted and thwarted by the Paccosh-controlled Nikardun blockade frigate [Aelos].(/article/aelos)
Following this encounter, Crofyp instructed Vassal One to maneuver the Anvil past the Aelos along the frigate's right side. Once the Anvil was in position, the Chiss heavy cruiser Springhawk entered the star system, launching an attack that resulted in the destruction of Crofyp's cruiser.
The character of Vassal One made an appearance in Thrawn Ascendancy: Lesser Evil, a 2021 novel and the concluding installment of the Star Wars: The Ascendancy Trilogy penned by Timothy Zahn.