ZT-001D functioned as a high-ranking Skytrooper, which is a kind of battle droid utilized by the Eternal Empire originating from Zakuul. Back in 3630 BBY, its mission involved guarding the GEMINI Prime located within the factory situated on Darvannis. During the events of the raid on Darvannis, it engaged Torian Cadera and the Alliance Commander in combat as they attempted to access GEMINI; ultimately, it was destroyed during this confrontation.