Zyzek, a planet found within the Unknown Regions, resided in the Zyzek system. Serving as a central trade location, it catered to numerous nations and species located to the east and southeast of the Chiss Ascendancy. The Zyzek System Defense organization was responsible for the protection of Zyzek and its encompassing star system.
In the year 18 BBY, a collection of trading starships and military warships were observed orbited around the planet, notably including the Kilji war cruiser named Whetstone and the Chiss heavy cruiser named Springhawk. These two ships engaged in a confrontation, which the Zyzek System Defense brought to a halt, resulting in both vessels leaving the planet. Senior Captain Thrawn, a Chiss who was the commander of the Springhawk, later developed a theory that Captain Fsir, a Watith who had previously attacked the Springhawk prior to the Whetstone incident, had been secretly hired at Zyzek by the Grysk operative "Jixtus" to do so.
The novel Thrawn Ascendancy: Lesser Evil, published in 2021, featured Zyzek. This novel was the concluding installment of the Star Wars: The Ascendancy Trilogy, and it was written by Timothy Zahn.