The R4 courier droid, alternatively known as the Imperial courier droid or the Imperial communication droid, represented a specialized adaptation of R4 astromech droids by the Galactic Empire. Their primary function was to serve as couriers, physically transporting data between locations to circumvent network usage. These droids were identifiable by the Imperial Press Corps insignia, granting them access to highly classified information, and frequently displayed distinctive markings for easy identification. Following Grand Moff Wilhuff Tarkin's directive to destroy Lothal's Imperial Communications Center, the Empire resorted to employing R4 courier droids to move data to and from the planet's surface.
The purpose of R4 courier droids was to move information physically when standard computer networks were unavailable. These droids were typically modified astromech droids that had unique markings to tell them apart. The Empire didn't give their courier droids personalities. As a result, they could only communicate using yes or no beeps.
In 4 BBY, after Grand Moff Wilhuff Tarkin gave the order to demolish Lothal's Imperial Communications Center, Imperial authorities began utilizing R4 courier droids to physically transport sensitive information. The Spectres exploited this situation in an attempt to locate Kanan Jarrus, by stealing a courier droid designated 264 and replacing it with their own repainted droid, C1-10P. The rebel droid then infiltrated an Arquitens-class command cruiser orbiting Lothal, acquired intelligence regarding Jarrus' location, and subsequently returned to his own ship, the Ghost, which was under intense fire.
While aboard the Ghost, 264 surprised and impressed the rebel crew by assisting in extinguishing fires. The crew was so impressed that they considered making the Imperial droid a permanent member. However, the volatile C1-10P could not accept this and ejected his potential rival out of the cargo doors while the ship was in flight. On the grasslands below, two Loth-cats were surprised when 264 plummeted from the sky into their midst. The droid survived the fall, and righted itself, finding itself in curious company.
On multiple covert operations, Chopper was disguised as an R4 courier droid. This allowed Chopper to infiltrate and destroy an Imperial Interdictor within the Del Zennis system during 3 BBY. Later, in 2 BBY, Chopper was again disguised as an R4 courier droid during a mission led by Hera Syndulla and Ezra Bridger to recover a family heirloom, the Syndulla Kalikori, from Grand Admiral Thrawn. Chopper's disguise successfully deceived the stormtroopers guarding the former Syndulla residence, enabling him to strategically plant explosives throughout the building to facilitate Hera and Ezra's escape.
The Galactic Empire also stationed several R4 courier droids at the Imperial Armory Complex in Capital City of Lothal. During a mission to infiltrate the factory, Chopper was disguised as a courier droid. To gain access to Section A2 and steal secret Imperial plans, Chopper used electrocution on an R4 courier droid and stole its clearance code. Despite the disguise, Thrawn realized that an unauthorized C1-series astromech droid had broken into the chamber and stolen his blueprints for a prototype starfighter.
The initial appearance of the R4 courier droid occurred in "Rebel Resolve," the fourteenth episode within the canon animated series Star Wars Rebels' first season. Additional information about the droid was provided in a Databank entry and Michael Kogge's chapter book Battle to the End, which summarizes the plot of several Star Wars Rebels episodes including "Rebel Resolve." R4 courier droids also appeared in "An Inside Man," the eighth episode of the third season of Star Wars Rebels.