There were numerous types of battle droids. They predated the Galactic Republic by thousands of years, with the earliest known being Rakatan guardian droids and the war-robots used by Xim the Despot. The Eternal Empire used battle droids known as Skytroopers as their primary infantry units. Many of the best known battle droids were those used by the Confederacy of Independent Systems during the Clone Wars. At the end of the Clone Wars, Sith Lord Darth Vader turned off the Master control signal, deactivating most of the Separatist Droid Army. After this, battle droids were extremely rare.