Stygeon, more formally known as Stygeon Prime, was a frigid, mountainous planet situated within the Stygeon system. This system itself resided in the Nuiri sector of the Outer Rim Territories. Due to the world's constant blizzards, it presented an ideal setting for a prison. Any inmates attempting to flee would face almost certain death outside the prison's confines, unless they possessed a Tibidee capable of carrying them to safety. During the Clone Wars, the Sith Lords Darth Tyranus and Darth Sidious imprisoned Maul, Sidious's previous apprentice, within the Spire. The Spire functioned as a Confederate prison located on Stygeon Prime. Later, Mandalorian forces belonging to the Shadow Collective executed a break out of Maul. Following the Clone Wars, the Galactic Empire took control of the planet.
Also called Stygeon, Stygeon Prime was a mountainous planet covered in snow, found in the Stygeon system, which is part of the Nuiri sector of the Outer Rim Territories. The diameter of this planet was 9,100 kilometers, and its Type I atmosphere consisted of a nitrogen, hydrogen, and oxygen mixture. Stygeon had a thin, chilly climate. Orbiting a single star and having two moons in orbit, Stygeon was largely without indigenous lifeforms, with the exception of the large tibidee creatures that considered the planet their home.
The planet Stygeon Prime, then simply called Stygeon, was initially referenced in the Blaster section of Star Wars Insider 149. This section provided information on the then-upcoming Star Wars: Darth Maul—Son of Dathomir miniseries. The planet made its debut appearance in the first issue of the series. The full name of the planet was revealed in Star Wars Rebels: The Visual Guide.