A Grysk military member, a soldier of the Grysk species, served under the Grysk operative "Jixtus" and was positioned on the planet Sunrise in the Unknown Regions circa 18 BBY. Their assignment was to maintain distance from the Grysk mines on Sunrise and the workers there, thus remaining uncounted in Jixtus's forces, which enabled the outriders to observe the mines.
Following the deaths of the majority of Grysk soldiers on Sunrise at the hands of the Paccosh species, the two Grysks encountered Pathfinder navigator [Qilori], who was an agent of Jixtus. They requested that he inform Jixtus of their readiness to eliminate his adversaries and deliver "the one" to him, but before this could happen, three Paccosh came near Qilori, causing the Grysks to take cover. Qilori subsequently communicated the outriders' message to Jixtus, who was uncertain about the meaning of "the one." The Grysk outrider was clad in armor.
The Grysk outrider made an appearance in Thrawn Ascendancy: Lesser Evil, a 2021 novel that concludes Timothy Zahn's Ascendancy Trilogy.