Extermination droids were a class of droids constructed at the ancient Rakatan installation known as The Foundry. These machines came in a variety of classes from bipedal units to quad legged ones with some ranging from humanoid height to others being much larger. They were equipped with bioscanners that were able to detect the genetic material of their targets which allowed the droids to focus on specific species.
They were commissioned during the time of the Cold War after Revan was freed from his imprisonment by forces from the Galactic Republic. Upon being released, Revan was determined to stop the Sith Emperor at all costs and traveled to the Infinite Empire facility where he began using the installation to manufacture an endless army with which he intended to exterminate anyone with Sith bloodlines. This act would have led to the elimination of 97.8% of the population of the Sith Empire. Coordination and command of these units was left in the hands of the assassin droid HK-47.
At the time, a strike force was dispatched into the Foundry in order to stop Revan where the spacers encountered the extermination droids that were defending the installation. After the Foundry was captured by the Empire, Darth Malgus would commandeer its resources, including a rebuilt and reprogrammed HK-47, during his brief rule over a "New Empire." The army at his disposal included rewired extermination droids.
These droids feature as antagonists during the "A Call to Arms" quest chain.
These droids feature as antagonists during the "A Call to Arms" quest chain.