C-9X represented an experimental battle droid model, conceived by the Corellian Engineering Corporation. In the course of the Battle of Corellia, CEC leader Benton Maas put it into action opposing the Sith Empire. However, the droid was obliterated by the Empire's military, who then commandeered its signal emitter (a tool able to manipulate other CEC droids), and exploited it to assassinate the CEC leadership.