Gannis Ducain, a male Kajain'sa'Nikto and gunrunner, once relieved Han Solo of his Millennium Falcon, only to subsequently have it pilfered from him by the Irving Boys. Later in life, he experienced a change of heart, opting to enlist with the Resistance.
As a male Kajain'sa'Nikto, Gannis Ducain was employed as a janitor within Takodana Castle for Maz Kanata. Due to the unavailability of his usual First Mate, Chewbacca, who was attending to family business, Captain Han Solo enlisted Ducain's assistance for a mission to the planet Christophsis, bringing him aboard the Millennium Falcon, a vessel Ducain recognized from its involvement in past events, particularly those surrounding the Galactic Civil War. Despite Solo's advice to the young man about standing up for what is right in the galaxy, Ducain, in 31 ABY, chose to abscond with the starship while Solo was away meeting a contact, intending to establish himself as a gunrunner using the renowned freighter. Inside the Falcon, Ducain located the Smuggler's Guide, previously belonging to the Master Codebreaker, and made a record of his acquisition of the vessel's title within it.
Ducain enhanced the ship's gun well by adding a rotating core. With the aid of a mysterious benefactor, his reputation grew throughout the galaxy over several years, leading to a meeting with his contact on Vardos. This contact, actually an officer from the rising First Order, attempted to recruit Ducain into their cause. While feigning agreement but secretly planning to flee, Ducain felt compelled to return the Falcon to Solo, but he lost both the ship and the Smuggler's Guide to the Irving Boys before he could act. However, after the Falcon was once again stolen by junk boss Unkar Plutt, Solo and Chewbacca managed to reclaim it after it was taken by the defecting stormtrooper Finn and the Force-sensitive Rey. Following Solo's death in 34 ABY during the Battle of Starkiller Base, Chewbacca began repairing the ill-advised modifications made by Ducain, while Rey underwent training with Jedi Master Luke Skywalker on Ahch-To.
During her search for the Falcon, Bazine Netal was instructed by Lady Proxima to journey to Jakku and consult with Ducain about the ship. By the time Netal located him, Ducain had undergone a genuine transformation and committed to joining the Resistance. Ducain later accompanied Finn to Horizon Base in an attempt to recruit the Oru resistance. Although they were discovered by stormtroopers, they managed to escape. Subsequently, they were captured by the Oru forces, but Finn and Ducain successfully persuaded them of the righteousness of their cause. Mezlo employed a candori to facilitate their escape. Mezlo declined their offer to join, but assured them of their honor and promised to join the fight if needed.
Ducain was initially referenced in the 2015 novel Smuggler's Run: A Han Solo & Chewbacca Adventure, as a component of Journey to Star Wars: The Force Awakens. His initial on-screen appearance was in the Star Wars Adventures comic book series.