C2-B5 was a black-plated astromech droid in the service of the Galactic Empire. The droid was frequently subjected to memory wipes to keep it subservient, causing the astromech to have no distinctive personality. It was capable of deploying a large personal energy shield, scanning the area for hostiles, and releasing a poisonous dioxis gas.
The astromech was stationed in the Imperial facility near Fortress Vader on the planet Mustafar when agents of the Rebel Alliance infiltrated the base in 1 BBY. Later that year, C2-B5 was deployed in the Imperial security complex on the planet Scarif, patrolling for needed maintenance and performing computer network sweeps within the Citadel Tower's data vault. The droid was present in the Citadel when the Battle of Scarif broke out against the rebels, which culminated in the destruction of the entire base by the Empire's Death Star superweapon.