Sentinel (Contingency)

Sentinels were humanoid in shape, and their bodies greatly resembled the B1-series battle droids once used by the Trade Federation and the Confederacy of Independent Systems. However, contrary to those battle droids, sentinels were clothed in bright red robes that resembled those once worn by the Emperor's Royal Guard. Over those robes, some of them wore red jackets that had gloves built in. Others, however, had no such hand coverings.

Also unlike battle droids, sentinels had heads that resembled a with a smooth glass dome. Their glass masks were in fact screens used to display lifelike images of the late Palpatine's face. Finally, sentinels had human-like five-fingered hands with a holoprojector built at the center of their palms, and a retractable needle that allowed them to verify the identity of a message's recipient by analyzing their blood.

The sentinels were created as part of the Contingency. Most of them were merely messengers: they appeared, verified the identity of the message's recipient, gave commands, and left. The ones reserved for Gallius Rax, however, were much more independent and closer to actual sentience. They were also capable of piloting starships and of killing intruders when protecting secret assets.

The sentinels were also uniquely designed, with a core directive to express a particular emotion, speculated to be loathing or spite by The Surgeon. They also had access to a wide array of mathematical formulas used to measure an individual's loyalty (from the Emperor himself to the broader Empire), resourcefulness, and conscience. These formulas recognized variables such as past kills (during or outside of military service), disciplinary actions, family trauma, education, genetic predisposition, species predispositions, personal associations, history of obedience to unlawful commands, involvement (including nonparticipatory exposure) in physical interrogation, and MDC-count. The coding in a sentinel was ultimately designed to assess individuals as parts of units, and then render judgement on the units as a whole, determining the moral character of a battalion or fighter wing based on current or past leadership and membership. These calculations gave the most weight to a unit's worst members, tracing their corrupting influence on those around them. In essence, the sentinels were used to track down units most susceptible to corruption, and then exploit that corruption.

The sentinels were first made in or prior to 20 BBY, when Palpatine was still the Supreme Chancellor of the Galactic Republic engulfed in the pan-galactic Clone Wars against the Confederacy of Independent Systems. At the time, many were assigned to the protection of the recently built Observatory on Jakku, one of many similar buildings scattered across the galaxy. These sentinels were used to guard the Observatory and the various ancient Sith artifacts stored inside. The sentinels played an important role as transmitters of the Emperor's Contingency plan, which involved destroying the Empire in the event of his death and sending a few worthy Imperials into the Unknown Regions to rebuild the Empire.

In the days following the Emperor's death at the Battle of Endor, a sentinel traveled aboard a Lambda-class T-4a shuttle to the Star Destroyer Torment, captained by Lerr Duvat, at Rendezvous Point: Victim in the Outer Rim. The sentinel met Duvat aboard the ship's bridge, after Duvat had dismissed his officers. Upon verifying Duvat's identity with blood, the sentinel delivered a posthumous message from Emperor Palpatine, stating that Operation: Cinder was to begin immediately. The sentinel then presented Duvat with his target: the Mid Rim world of Naboo. Another sentinel was dispatched to Fleet Admiral Gallius Rax, who was tasked with carrying out the Contingency.

Another sentinel droid was dispatched to Admiral Garrick Versio and met him on the bridge of his Star Destroyer, the Eviscerator, above the admiral's homeworld of Vardos. Versio elected to share the Messenger's presence with his daughter, Iden Versio, who was a commander and head of the elite Inferno Squad. The droid delivered the first part of the message, to commence Operation: Cinder, to the pair; when Iden asked about the target the droid suddenly lunged aggressively at her declaring that she was not a verified recipient, startling both Versios. Unbeknownst to Iden, the target was in fact their own homeworld of Vardos, though Garrick did not share this information with his daughter.

One of the Messengers arrived in the hands of the 204th Imperial Fighter Wing, and it ordered them to commence Operation: Cinder. It then ceased to provide updates. After weeks, it served as a centerpiece of a shrine aboard the Aerie to what the Imperials had lost. After the Aerie was stripped of parts and served as a decoy during the Troithe operation, the Messenger survived the ship's destruction and was found by the wreckage of the Edict. It later had the misfortune of wandering upon Yrica Quell when she was in the midst of sending a signal to the New Republic, resulting it in being fatally shot and deactivated. It was then dismantled by both her and her commanding officer, Soran Keize before it's core parts were brought to a droid known as The Surgeon. It dissected the Messenger and gave crucial intelligence to Yrica Quell, who shortly afterward, shared the information with the New Republic and Soran Keize.

In 5 ABY, three months after Endor, the Rebel heroes Luke Skywalker and Shara Bey discovered a manufacturing line of sentinels while carrying out a mission to retrieve fragments of a Force-sensitive tree from an Imperial base on Vetine. The assembly line was destroyed during the confrontation between the Rebels and Commandant Hurron's troops.

In the lead up to the Battle of Jakku, a sentinel informed the now-Counselor to the Empire Rax that the deposed Grand Admiral Rae Sloane was approaching the Jakku Observatory with Niima the Hutt's caravan. During the Battle of Jakku, Rax traveled with the former Commandant Brendol Hux, his son Armitage, his child soldiers, and Adviser Yupe Tashu to the Observatory on a transport piloted by the sentinel. Using the sentinel pilot, Rax transmitted commands ordering the turbolasers and sentinel droid defenses to power down.

The sentinel pilot later piloted a replica of the Emperor's yacht Imperialis into the Unknown Regions. The ship's passengers included both the Huxes, the child soldiers, and Grand Admiral Sloane. During the journey, the sentinel told Sloane that a dozen path coordinates had been transmitted to Imperials considered loyal to the late Emperor. The droid informed her that all sentinels and messengers were programmed to serve his will even in death. After several months of traveling, the Imperialis rendezvoused with the Emperor's flagship Eclipse.

Years later, the B1 battle droid R0-GR wrote the droid guide "droidography." In the section describing the increasingly blurred line between organics and droids, he recounted that it was rumored Palpatine used sentinel droids bearing his image to deliver direct messages to officers. R0-GR felt this made the Emperor even more horrifying and included an image of a sentinel droid.

Sentinel droids first appeared in Shattered Empire 2, the second issue of the Marvel Comics miniseries Star Wars: Shattered Empire, which was released on October 7, 2015. The concept was written by Greg Rucka while the droids were drawn by Marco Checchetto.

• Ultimate Star Wars, New Edition
• Star Wars: The Secrets of the Sith
• Star Wars: Timelines
• "After Endor" — Star Wars Insider 222
• Star Wars: The Rise and Fall of the Galactic Empire