Shadow Number Two was the name given to a void in the Rapacc system's solar wind, within the Unknown Regions, created by one of the two gas giant planets residing there. During 19 BBY, Senior Captain Mitth'raw'nuruodo of the Chiss, whose core name was "Thrawn," embarked on a mission to this system, with the intention of guiding his warship, the Chiss heavy cruiser Springhawk, through it without being noticed. Consequently, he directed the ship to pass through a void called Shadow Number One, accompanied by Admiral Ar'alani's vessel Vigilant, utilizing the larger ship's visual presence for concealment. Once inside the Rapacc system, the Vigilant subsequently departed via Shadow Number Two, allowing Thrawn to proceed with his objectives.
The 2020 novel Thrawn Ascendancy: Chaos Rising, the initial entry in Timothy Zahn's Star Wars: The Ascendancy Trilogy, featured Shadow Number Two.