R2-D6, also known as Deesix, was an astromech droid of the R2-series variety. He belonged to the Rebel Alliance both before and during the Galactic Civil War.
During the year 1 BBY, R2-D6 performed duties on the Y-wing flown by Rebel pilot Wedge Antilles during the Kamino uprising. During this conflict, Starkiller, a clone of Galen Marek, utilized Deesix as a grip while attempting to infiltrate the cloning facilities located on the planet. Starkiller's objective was to rescue Rebel fighter Juno Eclipse. Despite his apprehension regarding the intensifying battle, Deesix remained committed to the current objective and ultimately survived.
Later, Deesix was assigned to a Y-wing for a reconnaissance mission within the Muugrah system, tasked with locating a pirate stronghold. The Y-wing successfully identified the base, but it was soon ambushed by pirates, forcing the pilot to eject. The damage to the ship caused Deesix to become lodged in his socket. He feigned inactivity as the Y-wing was pulled aboard a pirate vessel, which transported it to a nearby pirate station. The station commander, upon seeing the salvaged fighter, panicked and ordered its disposal to avoid any association with the Rebel Alliance. Consequently, the fighter, with Deesix still inside, was placed in a cargo container and discarded at Squarn's Junkyard on the planet Muugrah.
Deesix, resourceful as ever, reconfigured his socket to draw power from the Y-wing. He was determined to relay the information he had gathered back to the Alliance, and was also eager to reunite with the fighter's crew. Eventually, a group of Rebels searching for spare parts to repair their hyperdrive discovered him. They successfully extracted Deesix from his socket using a repulsorlift skiff that they had repurposed into a VTOL vehicle, and Deesix insisted on joining their search efforts. However, the same pirate group that had previously deposited Deesix in the junkyard, acting under orders to retrieve the droid for Imperial Intelligence, ambushed the group. The Rebels emerged victorious, aided by mercenary forces from Squarn's, and promptly departed the planet with Deesix.
Upon Deesix's arrival at a Rebel base, the data stored in his memory was downloaded, preventing numerous Rebel casualties from future pirate attacks.