The Grehollo system was located in the Mid Rim's Manoe sector. It contained the Imperial base known as the Grehollo station as well as the moon Captivity. The harsh conditions on Captivity allowed the Empire to use it to exile prisoners, with TIE fighters from the Grehollo station patrolling the prison moon.
The Rebel Alliance carried out a mission to the Grehollo system during the Galactic Civil War. A team of Rebel soldiers infiltrated the moon as exiles and located there a group of political prisoners important to the Alliance's cause. The freighter Millennium Falcon then transported both groups off Captivity and out of the Grehollo system.
The Grehollo system was located in the Manoe sector, a part of the New Territories portion of the Mid Rim. The Grehollo system contained the small terrestrial moon Captivity as well as the Grehollo station, a military base of the Galactic Empire. Captivity was covered in a layer of clouds and had frequent and violent storms, and its surface featured high mountains and jagged rock formations. The hostile conditions of Captivity made landing a starship there highly dangerous.
The Grehollo system also contained a prison planet.
The Galactic Empire used Captivity to exile prisoners who, for various reasons, had to be kept alive. The prisoners were dropped to the moon's surface in escape pods, and Imperial TIE fighters from the Grehollo station frequently patrolled the moon.
During the Galactic Civil War, the Rebel Alliance carried out a mission to rescue political prisoners on Captivity who were important to the Alliance's cause, such as exiled Imperial senators. A team of Rebel soldiers, posing as the leadership of Virujansi, a planet recently taken over by the Empire, convinced Imperial Major Lariss, the leader of the Imperial force on Virujansi, to exile them to Captivity. After arriving on the moon, the soldiers located the prisoners, and both groups were eventually extracted by the freighter Millennium Falcon, which transported them out of the system.
The moon Captivity was inhabited by several groups of prisoners, some of them Human. Eventually, the gang of criminals led by Andews Rolo exterminated all other groups, with the exception of a smaller group of political prisoners led by former Imperial Navy captain Dedelin.
The Grehollo system was introduced in The Star Wars Rules Companion.
The Grehollo system appeared in "To Free the Forgotten," a roleplaying game adventure published in the 1989 The Star Wars Rules Companion for use with West End Games' Star Wars: The Roleplaying Game. The adventure was written by Greg Gorden, who developed it from a story by Steve Gilbert and Michael Stern. In "To Free the Forgotten," the players acting as game-masters are encouraged to improvise the conditions of the Rebel escape from the Grehollo system. This article assumes the adventure plays out as described.
"Twinkle, Twinkle Little Star, How I Wonder Where We Are," a 1990 roleplaying game source article published in Voyages SF 13, placed the Grehollo system in a sector of the same name. Since the article was released outside of the Lucas Licensing process, its canonicity within the Star Wars Legends continuity was never confirmed, and the StarWars.com Online Companion to the 2009 reference book The Essential Atlas instead placed the Grehollo system, and therefore Captivity, in grid square K-7 as part of the Manoe sector. Jason Fry, co-author of The Essential Atlas, noted on the Jedi Council Forums of TheForce.net that the Manoe system was created for "bookkeeping purposes" so that every sector listed in the Online Companion would have at least one corresponding system, although Grehollo was also placed in the Manoe sector.