The Mizx were a sentient species of humanoids who were native to the swampy world called Randorn Two. The Mizx sometimes fell victim to a local predator known as the ibliton. Lacking the means to effectively defend themselves with their basic weaponry, the Mizx created myths to explain the creature's existence: they believed it was an embodiment of Hershoon the Destroyer, formed from his deranged soul through the use of magick. The Mizx conducted ritualistic cleansing funeral ceremonies for those killed in ibliton attacks, with the belief that this prevented their souls from being reborn as iblitons. The Mizx had interactions with the galaxy, notably with researchers who journeyed to Randorn Two to study the ibliton. Researchers from both the Galactic History Foundation and the Tyberious Institute of Xenobiology expressed interest in the origins of the ibliton.
Mizx lived communally in villages consisting of small dwellings. They had domesticated animals such as layalls and hecxts, which they kept in enclosures near their settlements. Mizx villagers cultivated harrowbane around these enclosures; this caustic plant held sacred significance for the Mizx, and its touch caused burns to the tentacles of the native predator, the ibliton. They possessed a rudimentary level of technology, which they utilized to craft simple weapons.
The Mizx possessed a rich mythology, incorporating elements like magick, souls, and sacred flora. A key figure within this mythology was Hershoon the Destroyer. The Mizx believed that as The Destroyer neared his end, he employed potent magical abilities to manifest aspects of his corrupted soul. They believed these aspects materialized as the ibliton, which perpetuated The Destroyer's legacy of corruption even after his death. The ibliton was a hybrid creature, combining features of cephalopods and crustaceans; its soft inner body was protected by a large, coiled shell, polished to a high sheen by its own digestive fluids, while segmented legs were covered in a chitinous exoskeleton. This protective armor, along with four large tentacles used for attack, positioned the ibliton as the apex predator of Randorn. The ibliton would raid Mizx villages, gaining a reputation for seemingly destroying solely for the sake of destruction. Mizx younglings were taught from a very young age to avoid venturing into the swamps and bayous of Randorn for fear of encountering an ibliton.
Mizx funeral rituals involved banishing ceremonies designed to purify the souls of Mizx who had been killed by iblitons. Their mythology stated that any Mizx soul that did not undergo this consecration would be reborn as another ibliton. The Mizx also held the harrowbane plant in high regard due to its defensive properties against the ibliton.
The Mizx evolved on the isolated planet of Randorn Two, situated in the Belderone sector within the Outer Rim Territories. They established a basic society, developing simple weapons and domesticating local wildlife. Their villages were occasionally attacked by iblitons, reinforcing their mythology surrounding the species' origins.
The Mizx had contact with the wider galaxy, and their planet was known during the time of the Clone Wars. Numerous researchers visited the planet to study the ibliton. Meslinger, from the Tyberious Institute of Xenobiology, unearthed ibliton fossils dating back millennia from the world's swamps, placing the species' origin around 600,000 BBY. While on Randorn, Meslinger witnessed an ibliton attack on a Mizx village. The research team managed to kill the ibliton only after firing multiple blaster shots. Their intervention saved the lives of all but one of the Mizx villagers, and the researchers were then able to observe the Mizx funeral rites. Meslinger published an account of the attack—one of only three published attacks—along with a detailed description of the funeral rites. Another researcher who took an interest in Randorn Two was Harzoon Parr of the Galactic History Foundation, who proposed that the ibliton had been introduced to Randorn by a lost spacefaring civilization.
Phil Brucato created the Mizx for the West End Games sourcebook Creatures of the Galaxy, which was released in 1994. Creatures of the Galaxy stood out because the text was written around the artists' creature designs, rather than the other way around, which was the standard practice for their sourcebooks. The Mizx were developed as part of the ibliton species' backstory, with illustrations by David Plunkett.