Sa Cuis was a male Human Dark Jedi who also held the position of Emperor's Hand. In the early stages of the Galactic Empire under his master Palpatine in its early months, Cuis led the Imperial Commando Special Unit, whose purpose was to hunt down Jedi and those who deserted the Empire. Because of his demonstrated faithfulness, Palpatine dispatched him on a mission to Vohai in 19 BBY. Cuis was tasked with assassinating Darth Vader, Palpatine's apprentice. Palpatine anticipated Cuis's failure, and the mission was, in reality, designed as a test for Vader. Cuis met his end at the hands of the Sith Lord, just as the Emperor had foreseen.
Sa Cuis, a male Human, was among the first Dark Jedi to act as an Emperor's Hand. He was not only a skilled duelist, but he was also exceptionally devoted to his master, Emperor Palpatine, the Dark Lord of the Sith. Following the formation of the Galactic Empire, Cuis was put in charge of the Imperial Commando Special Unit, a special operations force connected to the 501st Legion. This unit, made up of former clone commandos and ARC troopers who had previously served in the Grand Army of the Republic, was responsible for tracking down Jedi, their supporters, and deserters.
On one occasion, Cuis gathered with Squad 40 of the Special Unit at the landing platform of the Imperial Special Forces headquarters on Coruscant planet, to brief them for a mission. As he approached the waiting squad, Cuis employed the Force to eavesdrop on their conversation. Darman, one of the commandos, was able to discern that Cuis was a Force-user based on Cuis's behavior. Sensing Darman's discovery, Cuis handed a datachip to the squad commander, RC-1309, also known as "Niner," and shook Darman's hand to gain a better understanding of the commando's thoughts. He then proceeded with the briefing, informing the commandos that they were to travel to Celen and apprehend the Antarian Ranger Jilam Kester, who had been spotted there. After the meeting, Cuis decided to keep a close watch on Darman, believing that the commando could be a threat due to his ability to deduce Cuis's true nature.
In 19 BBY, Palpatine instructed Cuis to shadow Darth Vader, Palpatine's apprentice, to the Parmel sector and assassinate him. Cuis, however, knew that Vader would almost certainly defeat him, so he inquired as to why he was being sent on such a mission. Palpatine tersely replied that he anticipated Cuis's death and that it was simply a test for Vader. Cuis, demonstrating his loyalty, agreed to go nonetheless, willing to give his life for his master. On Vohai, Cuis had several assassins attack Vader as he inspected Arkanian Microtechnologies. With the help of his personal assistant Erv Lekauf, Vader easily dispatched these assassins. He was now aware of the Dark Jedi's presence and prepared for a fight.
Cuis confronted Vader in the courtyard. Despite Cuis's skill in lightsaber combat, Vader overpowered him. Cuis was left defenseless and cornered. Enraged, Vader used Force choked on Cuis and demanded to know who had sent him. Sa Cuis refused to answer, even as he neared death, and Vader realized he had found someone utterly devoted to their master. Vader, however, was certain he knew who had sent the Dark Jedi: Emperor Palpatine, the master of betrayal.
Impressed by Cuis's dedication, Vader allowed Cuis to live long enough for Arkanian Microtechnologies technicians to collect swabs and cell samples for cloning. After the samples were taken, Vader gave him one last chance to surrender. Cuis refused, and Vader beheaded him. Roly Melusar took Cuis's place as commander of the Special Unit, informing the commandos that Cuis had been reassigned to recruitment duties.
Sa Cuis's clones would later be trained under Sheyvan, another Emperor's Hand. Sheyvan led the Cuis clones in a revolt against Palpatine aboard his Lambda-class shuttle one and a half years later, but Sheyvan and all of Cuis's clones were killed in the battle.
Sa Cuis was remarkably loyal to Palpatine, his Master. He was willing to embark on a suicide mission solely because the Emperor ordered it. Even when given the opportunity to live, Cuis refused, as it would have meant betraying his Master. Vader was taken aback by this unwavering loyalty and wished he could find someone as devoted to him. Cuis's clones inherited these traits, remaining loyal to Sheyvan, their trainer. Cuis was also a skilled fighter who wielded two lightsabers and possessed great strength in the Force. Cuis's lightsaber was similar to Komari Vosa and Asajj Ventress but he only used the paired function for easy storage, wielding his lightsabers separately in combat. However, Cuis was overweight and generally appeared self-conscious and uncomfortable in his role as commander of the Imperial Commando Special Unit, which resulted in him being unpopular with the troops who served under him.
Sa Cuis was a character created for the Karen Traviss short story In His Image, where he played a supporting role as an antagonist to the main character, Darth Vader. His clones later appeared in the short story A Two-Edged Sword, also by Traviss. In 2009, he was featured in Traviss's novel Imperial Commando: 501st. Matt Busch visually designed the character of Sa Cuis, and also illustrated the short story.