Rbann was a Kubaz spy working as an agent for the Galactic Empire, specifically under the command of Blackhole. Blackhole, the enigmatic Director of Imperial Intelligence, dispatched him. In the year 1 ABY, Rbann was sent by Blackhole to Vorzyd V, a world known as the "Gambler's World". The Kubaz was given orders to locate and monitor prominent Rebel leaders Luke Skywalker and Leia Organa, whose presence on Vorzyd V to sabotage Imperial activities had been discovered by Blackhole. Rbann swiftly located them at the Casino Royale within Efavan, the capital city. His stormtroopers then subdued the Rebels and imprisoned them on Rbann's starship.
However, Luke Skywalker and Leia Organa successfully escaped, aided by their droid companions, C-3PO and R2-D2. Shortly thereafter, Blackhole received information that Organa had been abducted by the Freelies, a juvenile delinquent gang, who were holding her for ransom. Blackhole then instructed Rbann to apprehend a member of the Freelies in order to ascertain Organa's whereabouts. Rbann successfully tracked down a Freelie named Bemmie, but Blackhole's attempts to torture the young Vorzydiak were thwarted by Skywalker's intervention, who arrived and liberated the captive.
Gambler's World, a Star Wars Legends comic strip story arc, featured Rbann's debut and sole appearance within that continuity. The story was both written and illustrated by Russ Manning, and it was released in 1979.