The Shadowmen were humanoids native to the "night planet" of Nivek.
The Shadowmen were known as skilled hunters and trackers, and protected their property fiercely, using the darkness of their world to ambush enemies. They were high-tech hunters, employing sonic blasters and durasteel cable netting to capture foes.
During the Clone Wars, the Shadowmen allied with the Confederacy of Independent Systems, allowing the Separatists to construct a weapons facility on their homeworld. Roughly four months into the war, Obi-Wan Kenobi and Anakin Skywalker undertook a mission to Nivek to destroy the facility, and were attacked by the natives. Though they were unable to physically see their opponents, the Jedi used the Force to sense the Shadowmen, and were able to complete their mission.
- The Complete Star Wars Encyclopedia