D4-L1 was a droid specializing in data processing, belonging to Xira, who was part of the Free Ryloth Movement. He played a role in the movement's mission to assassinate Sheev Palpatine, the Galactic Emperor, and Darth Vader, the Sith Lord, by assisting Xira in organizing an assault on the Imperial Star Destroyer Perilous. This vessel was under the control of the Galactic Empire. A distinguishing feature of D4-L1 was the silver dome that sat atop him.