The Order of Shasa was a group of Selkath natives from the planet Manaan who possessed Force-sensitivity. They were deceived into working for Darth Sidious during his reign as head of the Galactic Empire.
The name of the Order of Shasa came from a Force-sensitive Selkath named Shasa. The Sith had enticed her, along with her companions, to visit the Sith Embassy situated on Manaan. The Sith intended to exploit the impressionable Selkath to topple the existing Manaan government, replacing it with young Force trainees who could be easily controlled. However, Revan uncovered the scheme and successfully persuaded the Selkath of the Sith's malevolent intentions. As punishment for the Sith's actions, which threatened Manaan's neutrality, restrictions were placed on their kolto shipments.

Following the conclusion of the Jedi Civil War, Shasa quickly came to the realization that if Manaan wished to maintain true neutrality in the future, the Selkath could not depend on the Jedi any more than they depended on the Sith. Given that Force-sensitive Selkath still required instruction and leadership to cultivate their abilities and avoid succumbing to the dark side, Shasa and the other Selkath who had been trained by the Sith formulated a doctrine centered around peace and defense. This led to the creation of an organization initially known simply as the Order. The Order established its secret base within an abandoned mining station located in the Hrakert Rift. However, with its limited number of members having received formal training in the ways of the Force from the Sith, the Order promptly recognized that the allure of the dark side posed a persistent threat. Those who had undergone Sith training found it challenging to disregard their initial teachings, and the Order of Shasa struggled to resolve these internal conflicts by pursuing a middle ground between the light and the dark. With the Sith's deception still fresh in her memory, Shasa initially refrained from seeking assistance from the Jedi or any other Force-using tradition. Nevertheless, when proponents of the dark side made substantial gains or began to influence new members of the Order, she did not hesitate to solicit guidance from a Jedi she trusted, or from another Force tradition with a positive reputation, such as the Jal Shey.
The Order persisted even after Manaan's influence in galactic affairs waned. During the Galactic War, the Order of Shasa took on the responsibility of defending an underwater laboratory where experiments were being conducted using Rakata technology. The purpose of these experiments was to engineer invincible supersoldiers for the Order of Revan's Infinite Army, under the direction of Revanites Darth Arkous and Colonel Rian Darok. Strike teams from both the Republic and the Empire, dispatched by Theron Shan and Lana Beniko, fought their way past the Order's adepts, and any surviving members presumably met their end when the Revanites intentionally destroyed the base.
By the time of the Galactic Empire, the Order boasted a membership of over two hundred adepts, a number considered remarkably high given the size of the Selkath population. Despite their numbers, they offered little resistance when the Empire subjugated their world.
Strangely, a significant number of them managed to evade the Empire's grasp for several years, until a mysterious figure made contact with them sometime before the Battle of Endor. This heavily cloaked Human, equipped with a rebreather, who was none other than Darth Vader, provided them with detailed intelligence about the guards, encouraged them, and instructed them to retaliate against the resort that had been constructed on Manaan during the Imperial occupation. Two hundred of the Order's most skilled members effortlessly navigated through Ahto's waste disposal system and swiftly eliminated the guards, forcing them into retreat. However, a peculiar bloodlust overcame the Order members, leading them to attack the resort guests, engaging in a frenzied slaughter reminiscent of sharks. Once the rage subsided, the Order members were filled with shock, but the enigmatic Jedi with the dark helmet and deep voice assured them that their vengeance would make them powerful, and that they would now serve the Emperor.
The Order of Shasa prioritized the safety and well-being of the Selkath above all else. The Order's storytellers preserved and passed down knowledge of the planet's history to younger generations, reinforcing the Selkath's dedication to Manaan. Each adept was assigned to a master, with the duration of training ranging from several months to several years.
A sword known as the fira held a similar significance to the Order as the lightsaber did to the Jedi. Each fira was unique, crafted by the trainee using rare materials as part of their training. The materials used in the fira were sourced from the old Hrakert Rift station, which had been destroyed by Revan in the past. The raw elements were shaped and tempered using volcanic vents on the ocean floor, making the process both dangerous and challenging. The construction of a fira signified true induction into the Order. This ritual was referred to as the Rite of Fira.
Driven by the Sith's deceitful actions during the Jedi Civil War, the Order of Shasa developed a potent Force-based ability to detect deception. They mastered a mind-affecting power known as the Progenitor's Call, capable of disrupting their enemies' actions. The Order was also recognized for a telekinetic technique they called a waveform, which involved manipulating environmental particles to amplify the impact of telekinetic attacks.