Vassek 3, alternatively called the third moon of Vassek, existed as a moon orbiting the planet Vassek. This planet was part of the Vassek system, which itself resided within the expansive Outer Rim Territories. During the tumultuous period of the Clone Wars, this moon became the site of the private fortress belonging to General Grievous, a leader of the Kaleesh within the Separatist Alliance. In the year 21 BBY of that era, forces of the Galactic Republic, commanded by Jedi General Kit Fisto, discovered that the fugitive Viceroy Nute Gunray of the Trade Federation was hiding on Vassek 3. The subsequent engagement with Grievous resulted in Fisto's forced retreat from the moon, making him the Republic's only survivor of the conflict.
Recognized also as the third moon circling Vassek, Vassek 3 was one of the three moons that orbited the planet Vassek. This planet existed within the star system also called Vassek, a location found in the Wazta sector of the Outer Rim Territories. Located at coordinates I-17 on the Standard Galactic Grid, the moon possessed a standard level of gravitational force and an atmosphere suitable for breathing. These conditions made it reasonably habitable for the majority of the galaxy's beings who required oxygen to survive. Vassek 3, along with the rest of the Vassek system, was situated far enough away from the heavily traveled Koda Spur hyperspace route that it did not receive a large number of visitors.
The moon was characterized by thick, persistent fogs and a near absence of vegetation larger than lichens. These mists also obscured the satellite's surface from observation from space, allowing only brief glimpses of its rocky terrain through breaks in the fog. Furthermore, attempting to land on the surface of Vassek 3 was made difficult by these vapors, which necessitated the use of scanning equipment and sensor arrays by pilots in order to identify appropriate landing zones. Vassek 3's landscape was defined by jagged, moss-laden, and fog-filled canyons, as well as towering rocky mountains with sharp peaks, deep gorges, and high columns of rock.
At some point during the Clone Wars fought between the Galactic Republic and the Confederacy of Independent Systems, General Grievous of the Separatist Kaleesh forces established a personal fortress on the surface of Vassek 3. Throughout the duration of the conflict, this fortress served Grievous as a place to rest between battles, a secure refuge, and a location where his cybernetics could be repaired when damaged in combat.
In 21 BBY, Jedi General Kit Fisto traveled to the Vassek system in pursuit of Trade Federation Viceroy Nute Gunray. Gunray had previously escaped from the Republic with the assistance of Separatist forces. Fisto tracked a tracking beacon from a Republic vessel used in Gunray's supposed escape to the third moon of Vassek, and subsequently landed there in his personal starfighter. Upon landing, Fisto encountered his former Padawan, Jedi Knight Nahdar Vebb, along with a detachment of clone troopers under the command of Clone Commander Fil. These forces had arrived on the moon via a Republic shuttle.
Unaware of their location, Fisto and the Republic task force entered Grievous's fortress, continuing their search for Gunray. As they moved through the citadel, the Jedi and the troopers overheard the viceroy issuing commands to several B1-series battle droids. The Jedi quickly destroyed these droids, only to discover that Gunray had been communicating via a hologram. In the transmission, Gunray was replaced by Count Dooku, the Confederate Head of State, who offered Grievous as an alternative target. The task force then learned that Grievous owned the citadel and had recently arrived in orbit around Vassek 3. Fisto, Vebb, and the clone troopers began to prepare an ambush to capture the general.
As Grievous entered the citadel, Fisto and the task force revealed themselves and demanded his surrender. Grievous responded by engaging the Jedi and troopers in combat, killing several clones and sustaining damage to his cybernetics. This forced him to retreat for repairs, which were administered by his medical droid, EV-A4-D. After his repairs, and following the death of Commander Fil by Grievous's pet roggwart, Gor—who was subsequently killed by Fisto—Grievous left his command center and fought and killed Vebb. After the death of his former Padawan, the Jedi Master attempted to escape the moon, but was briefly confronted by Grievous in the moon's mists. Despite Grievous's efforts, Fisto managed to escape in his starfighter, becoming the mission's sole survivor. After Grievous pursued the Jedi from the moon, he abandoned his fortress and relocated elsewhere, also repairing his destroyed doctor, due to the Republic discovering his base.
Hidden within a mountain on Vassek 3 was the personal fortress of General Grievous. He would return to this citadel between engagements in the Clone Wars to rest and repair his cybernetic limbs. The fortress was a gloomy and oppressive structure filled with deadly traps, and it also served as the home of Gor, Grievous's roggwart pet. The fortress was guarded by several IG-100 MagnaGuard droids and maintained by at least five B1-series battle droids and Grievous's EV-series medical droid, EV-A4-D, who was responsible for repairing any damage to Grievous's cybernetics.
Vassek 3 was first seen in the opening newsreel of "Rookies," the fifth episode of the Star Wars: The Clone Wars television series' first season. This episode was broadcast on October 24, 2008. The moon then made its full debut in "Lair of Grievous," the tenth episode of the first season, which aired on December 12, 2008.
Within the new Star Wars canon, Vassek 3 was identified in the 2017 reference book Star Wars: The Visual Encyclopedia. In the Star Wars Legends continuity, the StarWars.com episode guide for "Lair of Grievous" specified that the natural satellite was the third moon of Vassek.