Courier droids, which are also referred to as messenger droids, were a type of droid designed to physically move communications from one place to another. Various models were produced for this purpose, such as the ASN courier droid and the KUP24 messenger. Modified versions of R4-series astromech droids were utilized as courier droids by the forces of the Galactic Empire.
Numerous distinct types of messenger droids could be found operating throughout the galaxy, each one built to carry information. A notable example was the ASN courier droid, a diminutive flying droid measuring 0.3 meters tall; it featured a small compartment for holding messages during transit. Interestingly, these droids could be altered to serve as assassins, delivering lethal substances from the same message container.
The KUP24 messenger was a squat, compact model that moved close to the ground, and was used as forced labor by the Pyke Syndicate within the dangerous Spice Mines located on Kessel.
MSE-6 series repair droids, more commonly known as mouse droids, were small, wheeled general purpose droids with black plating that performed a variety of tasks, including message delivery within military bases.
The Galactic Empire's Imperial Press Corps made use of specialized R4-series astromech droids as courier droids. These droids were intended to transport confidential data between distant locations, bypassing standard communication networks. The Empire specifically programmed these R4 courier droids to lack any personality traits, and they were easily identifiable by special markings that indicated their role as couriers.