Mustafarians were a sentient species of insectoid beings. Originating from the volcanic world of Mustafar in the Outer Rim, a location known for its mining operations, they had two separate subspecies: the slender, towering Northern Mustafarians, and the compact, robust Southern Mustafarians. They were native to the planet.
As an insectoid and sentient species, Mustafarians were famous for their resilience and adaptation to the harsh, high-temperature environment of their homeworld, Mustafar. The two subspecies each had unique roles in their society and possessed different physical features. Northern Mustafarians were taller, reaching approximately 2.3 meters in height, while the shorter and stronger Southern Mustafarians typically grew to 1.5 meters. The Northerners were less resistant to high heat compared to their Southern counterparts, whose durable skin provided better protection. Both varieties of Mustafarians possessed skin that could withstand blaster fire, but they still relied on armor for protection when working near hazardous lava. Certain Mustafarian clan leaders were known to wield the Force to control lava.
Mustafarians made their homes in subterranean caves formed by indigenous lava fleas as they tunneled through the planet's crust. They primarily resided in underground structures resembling kahel cave fungus. Most Mustafarians only surfaced to extract valuable minerals from the lava flows or to participate in a coming-of-age ritual. This ritual involved a young Mustafarian riding a lava flea and leaping over a flowing lava stream without any protective gear. Northern Mustafarians often became guards and skilled lava flea riders, whereas Southern Mustafarians were responsible for heavy labor, though they were also capable of riding lava fleas. The Mustafarian species communicated using an insect-like, buzzing language of the same name.
Mustafarians commonly crafted armor from the heat-resistant shells of lava fleas and wore breath masks when working near lava, giving them a mysterious and uniform appearance to outsiders. Many Southern Mustafarians on the surface, transported on heat-shielded vehicles, wore this protective armor to scoop lava into massive cauldrons attached to metal rods, which were then transported by DLC-13 mining droids.
Despite evolving separately in Mustafar's underground caves, the Northern and Southern Mustafarians collaborated to extract valuable minerals from the lava flows of their homeworld and maintained a trade relationship with the Techno Union. Consequently, some aligned with the Confederacy of Independent Systems during the Clone Wars. At the war's conclusion, several Mustafarians who were with the Separatist Council on Mustafar were murdered by Darth Vader during his mission to eliminate the council, which had sought refuge on Mustafar.
Years later, Vader returned to Mustafar aboard a Naboo Royal Starship. A Mustafarian chieftain named Kkkt noticed the ship descending towards the surface and dispatched a scouting party to investigate. This party, consisting of four Mustafarians—Bbbl, Rrrn, Sssp, and one other—was attacked by Vader, who killed Bbbl and the unnamed Mustafarian. He then used a haunted Sith mask to possess Sssp, leading Rrrn to flee back to Kkkt and report what he had witnessed.
Soon after, Vader and the Sith spirit controlling Sssp began constructing a structure to harness the dark side energies from a Sith cave. When the structure failed to properly channel the energies, it was destroyed, and the two Sith began again. These attempts also impacted the rest of Mustafar, causing lava storms to erupt across the clans' territories. Kkkt contacted the other clans, and they devised a plan to destroy the structure before it destroyed their homes. Kkkt led this newly formed army to attack the recently constructed fortress. Despite outnumbering the Imperial garrison ten to one, Vader slaughtered many of them. Kkkt and the other chiefs then used the Force to direct a lava flow, flooding the battlefield. With the garrison eliminated, Vader retreated to the fortress, and Kkkt's remaining forces attempted to destroy it. However, Vader channeled the Force through the fortress, obliterating the last of the Mustafarian army.
Kkkt was not the final Mustafarian to assault the fortress, as Criakan also led his own army in an attempt to destroy it. Upon entering, they overwhelmed the defending lava troopers and discovered Vader's aide, Vaneé. Criakan threatened Vaneé, who pointed out Vader standing behind the Mustafarians. Vader then proceeded to kill the invaders. Priestess Sssl of Clan Rrrt also led an attack on the fortress, leading an army of plague-infected Mustafarians to infect troopers around the complex and break into it. Vader confronted them and was bitten by one of the infected troopers. However, the bite was only on his cybernetic arm, and Vader used the Force to control the infected Mustafarians, forcing them to destroy Sssl and themselves.