General Grievous was developed for Revenge of the Sith as a powerful new villain on the side of the Separatists. The initial instructions that director George Lucas gave the Art Department were very open-ended: «a droid general». From that vague direction, the artists developed a lot of explorations, some purely mechanical, some not, for Grievous’ look. He was also created as a villain foreshadowing Anakin Skywalker’s transformation into Darth Vader: the heavy breathing, the cyborg body and his seduction into an evil faction.