The BT-1 Assassin Droid was an new model of Assassin Droid that was created to look like an Astromech Droid and was loaded with multiple weapons including a rocket launcher that can tear through an Imperial-I Class Cruiser and a flamethrower. Only one prototype unit was used by Darth Vader along with his ally, Doctor Aphra and her modified protocol droid, 0-0-0. BT would later form a bond with 0-0-0 and become under ownership of Aphra and her secret Droid Division.