The Pitrillistians were sentient humanoids who stood seven feet tall and had purple, two-piece shells. Under these carapaces, they had small wings that allowed them to communicate. They used their proboscises to extract minerals from fluids. The species' anatomy featured two completely different fine manipulators. The left was more insectoid in nature, sporting two long pincers. The right, however, boasted a more humanoid hand with four fingers, which allowed them to wield blasters and the like. Their feet ended in sharp claws. The Pitrillistian face was red, with green hair along the snout. On either side of the head were two large bluish-white horns, which hung down to the individual's hips. Between their shells was a large tuft of brown fur, and on either wrist was a similar tuft of white fur.
The Pitrillistians were native to Pitrillistia, a world located on the edge of the galactic border, in the Mieru'kar sector of the Outer Rim Territories. By 4 ABY, the species' homeworld had fallen into territory controlled by the Imperial faction known as Oversector Outer; however, the region was largely neutral by 7 ABY.
The Pitrillistians were created by Desset Fabien through the "Design An Alien" competition run in the Star Wars Galaxy magazine. The competition, launched in Star Wars Galaxy Magazine 3 (1995), called for readers to create completely new alien species inspired by the original trilogy of Star Wars films. Fabien was nineteen years of age when he submitted his entry, which was later published in Star Wars Galaxy Magazine 7 (1996) under the "honorable mentions" section of the "16 and over" subdivision. Continuity editor Leland Chee later stated that published material from the "Design an Alien" competition was considered canon. The planet Pitrillistia, which was created by Fabien in his submission, was later included in The Essential Atlas (2009), written by Jason Fry and Daniel Wallace.