CS-321, a RA-7 protocol droid with a tan exterior, served the Weequay pirates during the Clone Wars. This conflict pitted the Galactic Republic against the Confederacy of Independent Systems, a group that had seceded from the Republic. CS-321 met his end in a battle between these warring factions.
CS-321 fell into the hands of Weequay pirates at some point during the Clone Wars. More than a year into the war, CS-321 was aboard the pirate ship named Marauder, witnessing a droid gladiatoral combat event. During this event, R2-D2 and C-3PO, who were captured on Balnab, were brought onto the pirate vessel. CS-321, together with R2-D2 and C-3PO, watched the K0-5D warrior droid compete against other droids. Just as Artoo and Threepio were about to enter the arena, General Grievous and the Separatists used the Marauder for target practice. A laser blast breached the Marauder, causing everyone on board to be expelled into space. The Separatists captured the droids, intending to incinerate them. CS-321 resisted incineration and was subsequently shot down by battle droids.