11-4D, a protocol droid, provided services to Darth Plagueis in the years leading up to the ascension of the Galactic Empire. Sometime before the [Clone Wars](/article/clone_wars], his Sith apprentice, Darth Sidious, murdered Plagueis, inheriting 11-4D as a result. Programmed to serve its new master, the droid faithfully served Sidious for numerous years.
The Sith Lords Darth Plagueis and his apprentice Darth Sidious both benefited from 11-4D's services. Following Darth Sidious's act of killing his own master, 11-4D continued its servitude to Sidious, taking on various roles. In the public eye, Sidious adopted the guise of Senator Sheev Palpatine from Naboo, eventually ascending to the position of Supreme Chancellor after the Battle of Naboo. Sidious skillfully orchestrated the Separatist Crisis, which resulted in the formation of the Confederacy of Independent Systems and the devastating [Clone Wars](/article/clone_wars]. Sidious exploited the clone Grand Army of the Republic to annihilate the Jedi during the Great Jedi Purge. Subsequently, he declared himself Emperor, transforming the Republic into what would become the first Galactic Empire.
By 14 BBY, 11-4D was stationed at the Imperial Palace, previously known as the Jedi Temple. 11-4D also accompanied his master in Sidious's hidden sanctuary, a compact, rock-lined chamber located far beneath the temple, which had once been an ancient Sith shrine that the Jedi had built upon. After the Emperor sent Moff Wilhuff Tarkin and Darth Vader on a mission to the planet Murkhana, 11-4D informed Sidious that Tarkin had departed aboard his starship, the Carrion Spike. Sidious instructed the droid to notify him upon the ship's arrival on Murkhana. Following this, Sidious returned to his meditation.
After Berch Teller, an insurgent, and his rebel cell successfully stole the Carrion Spike, 11-4D was present during a meeting between Sidious and his Joint Chiefs, which included figures such as Admiral Conan Antonio Motti, General Cassio Tagge, Rear Admirals Kendal Ozzel and Tiaan Jerjerrod, COMPNOR Director Armand Isard, Imperial Security Bureau Deputy Director Harus Ison, Colonel Wullf Yularen, and Naval Intelligence Vice Admirals Dodd Rancit and Terrinald Screed.
During the assembly, 11-4D inserted one of its appendages into an interface socket, which then routed holofeeds from the former Jedi communications suite to the summit. 11-4D also followed the Emperor's instructions to darken the windows. The Emperor and the Joint Chiefs observed footage of the Carrion Spike attacking TaggeCo mining facilities located on Lucazec. When the Emperor inquired whether 11-4D had deduced the unfolding events, 11-4D confirmed that it had and reported that the holovid was being transmitted by the Carrion Spike. In response, Sidious dispatched reinforcements, including one of Darth Vader's black Eta-2 Actis-class light interceptors, to assist Tarkin and Vader.
Later, 11-4D was present when Sidious interrogated the ISB case officer Stellan and the Koorivar informant Bracchia regarding the discovery of the communications cache on Murkhana, which had ultimately led to the theft of the Carrion Spike. The two individuals confirmed that they were acting upon information provided by Military Intelligence, of which Naval Intelligence was a subdivision. Satisfied with their explanation, Sidious instructed 11-4D to examine the holovid sent by Military Intelligence to the ISB. When 11-4D indicated that it could not locate any record of the holovid, Sidious clarified that the video was stored within the ISB's archives. After 11-4D retrieved the holovid, Sidious determined that it was a forgery created by someone with access to Imperial codes and technology capable of compromising the HoloNet.
Subsequently, Vader and Tarkin uncovered that Rancit was a traitor who was providing intelligence and weaponry to Teller and his insurgents in an effort to elevate his own position within the Imperial Ruling Council. While Vader executed Rancit, Tarkin successfully suppressed Teller's rebels during the Battle near the Gulf of Tatooine. The defeat of Teller's insurgency resulted in Tarkin's promotion to Grand Moff and enabled the Empire to proceed with the construction of the original Death Star.
Throughout its service, 11-4D served both Darth Plagueis and his successor, Darth Sidious, seemingly adopting different forms over time. The droid possessed significantly more arms than a standard protocol model, with only two terminating in hand-like appendages. The remaining arms were equipped with various tools, including computer interfaces and power charge extensions. 11-4D once oversaw the excavation and restoration of Sidious's personal sanctuary: an ancient Sith shrine located deep beneath the Imperial Palace. Additionally, the droid acted as Sidious's servant, assisting him with tasks such as relaying holofeeds and retrieving holovids.
11-4D made its debut in the current Star Wars canon in the 2014 novel Tarkin, authored by James Luceno. Prior to this, 11-4D initially appeared in the 2012 Star Wars Legends novel Darth Plagueis, also penned by Luceno.
During a 2012 question and answer session held on Facebook, Luceno suggested that 11-4D was present during Anakin Skywalker's transformation into Darth Vader, as depicted in a scene from the 2005 film Star Wars: Episode III Revenge of the Sith.