A battle droid (also referred to as war droid or killer droid) is any droid designed for combat. There are numerous types of battle droids. They predated the Galactic Republic by thousands of years, with the earliest known being Rakatan ancient droids and the war-robots used by Xim the Despot. 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 are extremely rare.