The Coloi, alternatively referred to as the Coloi Rancor, represented a unique form of mutant Rancor brought into existence by the Sith Lord known as Quorlac Fornayh. In the era extending back over a thousand years prior to the Galactic Civil War, Fornayh devised a scheme to utilize this creature as a means of overthrowing the then-established Sith Empire. To achieve this objective, he initiated the development of the Coloi through the application of Sith alchemy, operating from within a fortress situated on the planet named Yorgraxx. Initially, Fornayh focused on enhancing the rancor's cognitive abilities. Subsequently, he modified its skeletal structure to be lighter and added sizable wings, granting it the capability of flight. Following this, he replaced its natural hide with a layer of black metallic plating, designed to function as armor. All of the alterations implemented were genetic in nature, with the intention of enabling the breeding of additional Coloii. However, by the time Fornayh had successfully refined the creature's design, the Sith Lord was nearing death. Consequently, he placed the Coloi in a state of stasis within his fortress. Although he had intended to train the creature in the use of blasters and other armaments, his impending demise prevented him from doing so. Instead, he established rapid-learning facilities within the fortress to educate the Coloi template.
In the year 32 BBY, amidst the Trade Federation's occupation of the planet Naboo, a Coloi was transported to the city of Theed. During an armed conflict involving B1-series battle droids against a combined force of Gungan and Naboo Security officers, an errant blaster shot struck the Coloi's enclosure, leading to its escape. Subsequently, the Coloi engaged in a destructive rampage, resulting in substantial damage valued at numerous credits.
During the era of the Galactic Civil War, Fornayh's spectral essence was revived when a ship experienced a crash landing on Yorgraxx, leading him to reanimate his Coloi. However, the creature met its end at the hands of a coalition of Imperials and Rebel Alliance members who had infiltrated Fornayh's stronghold and confronted him directly.
Robert Wiese conceived the Coloi, which made its initial appearance in the 2004 role-playing adventure titled Shadows in the Force. Later, it was featured in the 2012 video game Kinect Star Wars, where it was available as a playable character within the game's "Rancor Rampage" mode.