Selsor was a planet, an astronomical body situated within the Selsor system. This system resided within the Zarracina sector, which itself was a component of the Trailing Sectors region of the Expansion Region. This world was characterized by the presence of multiple continents.
During the time when the Galactic Empire was in power, specifically within the reign of the Empire, the Snow Hawks, an Imperial cold assault stormtrooper squad, successfully executed a winter military operation. This campaign took place on the icy landscape of Selsor's main continent.
The first mention of Selsor occurred in Rules of Engagement: The Rebel SpecForce Handbook. This sourcebook, created by Timothy S. O'Brien for Star Wars: The Roleplaying Game, was published in 1997 by West End Games. Later, in 2009, The Essential Atlas reference book established the location of the Selsor system, and consequently the planet Selsor, within grid coordinates O-14.