S'ybll, a Mind-witch, spent countless years on the world of Seidhkona before encountering an exploration party dispatched by the Galactic Empire. She drained the life force of the Imperial team, an act that rejuvenated her. Driven by a desire for more life energy, she found the crew of the Millennium Falcon, who had sought refuge on her planet for repairs. Sensing the potent Force abilities of the young Jedi Luke Skywalker, S'ybll lured him into her territory. There, she employed Force illusions to ensnare Skywalker and steal his energy. However, Skywalker saw through her deceptions and ultimately triumphed over her.
Some years later, S'ybll journeyed to Tarnoonga, where she managed to siphon life energy from another group of Imperials. She then enticed Skywalker to the planet, confronting him at an Imperial outpost. Instead of seeking vengeance, S'ybll proposed an alliance with Skywalker, requesting that he bring her Imperials to drain in order to maintain her youth. Upon Skywalker's refusal, S'ybll attempted to drain his life force once more. However, the assault failed, and Skywalker ended her life by impaling her with his lightsaber.

S'ybll belonged to the mind-witches, a race of humanoids distinguished by their exceptional psychic gifts and extended lifespans. She also possessed telekinetic talents, enabling her to manipulate objects with her mind. At some point in her life, S'ybll came across colossal stone pillars on the planets of Tarnoonga and Seidhkona that amplified her telekinetic abilities significantly. Desiring to remain near her source of power, S'ybll established her home on Seidhkona. Although the city containing the stone columns gradually deteriorated over the years, S'ybll remained within its boundaries, considering the ruins her home. By the time of the Galactic Civil War, S'ybll, now quite old, still dwelled on the planet. To her surprise, an Imperial exploration team arrived on Seidhkona aboard a Lambda-class T-4a shuttle. As the Imperials explored the ruins that S'ybll called home, she employed her psychic abilities to seize control of their minds and drain their life energy. After eliminating the entire scouting party, S'ybll was delighted to find herself rejuvenated. Eager for more victims, S'ybll awaited the arrival of additional individuals to drain. While waiting, she crafted scarecrows from the stormtrooper armor of the Imperials and positioned them around her territory.
Around 3 ABY, S'ybll observed the Millennium Falcon landing on Seidhkona. The Rebels Luke Skywalker, Chewbacca, Han Solo, and their droids, R2-D2 and C-3PO, had landed to repair their damaged navigation computer. Sensing the potent Force within Skywalker, S'ybll was drawn to the ship. When Skywalker left the Millennium Falcon to scout the area, S'ybll read his mind and used her powers to create an illusion of Tanith Shire, one of the young Rebel's love interests. The illusion depicted Shire being attacked by a large plant beast, which Skywalker destroyed with his blaster pistol. S'ybll, maintaining the illusion of Shire, led Skywalker on a chase that ended with them diving into a river near her domain. After exiting the water, S'ybll dropped the illusion but explained the change in appearance as a result of the planet's unusual atmosphere. Skywalker accepted the explanation and followed S'ybll to her home. Skywalker was curious about the ruins and the stormtrooper scarecrows, but S'ybll evaded his questions, leading him deeper into her home. When Skywalker noticed the damaged Imperial shuttle, S'ybll claimed that it had been there long before her arrival and that she had simply used the armor inside to make the scarecrows.

As Skywalker sought more information about the fate of the Imperials, S'ybll drew him close. Claiming to need protection from the jungle's dangers, she kissed Skywalker deeply. However, he gently declined her advances, stating that he would help her but had other obligations. Upon his refusal, S'ybll stole his comlink and disappeared into the trees to create another illusion. Using memories stolen from Skywalker's mind, she conjured the Night Beast that he had previously defeated on Yavin 4. Skywalker fled from the beast, and while attempting to climb one of the ruins, the structure collapsed, incapacitating him. S'ybll used this opportunity to extract another image from Skywalker's mind, that of his deceased Jedi Master, Ben Kenobi. S'ybll's Kenobi illusion, in the form of a Force ghost, persuaded Skywalker to stay and seek out S'ybll. As Skywalker listened to the illusion, S'ybll siphoned his life energy, weakening the young Rebel.
As Skywalker collapsed, injured from his fall and weakened by the loss of his life energy, S'ybll gathered him and took him to her hiding place, where she placed him on a stone table to completely drain him. S'ybll's energy was dwindling, and her appearance began to revert to her haggard state with long white hair. To conceal her true form from Skywalker, she covered his eyes with a cloth. During this process, Skywalker awoke but was unable to move due to S'ybll's manipulation, who convinced him that she was trying to heal him. However, Skywalker's comlink, which S'ybll had kept to lure his companions after draining him, suddenly began to transmit communication. Skywalker's droids, R2-D2 and C-3PO, hoping to contact their missing master, called out from the comlink, and S'ybll could no longer restrain Skywalker. As he attempted to retrieve the device, the young Rebel pulled the cloth from his face, revealing S'ybll's withered appearance. With her scheme exposed, the Mind-witch snatched the comlink away from Skywalker, preventing him from contacting his friends.

Skywalker attempted to resist her power, but he was too weak to break the psychic link she had established within his mind. As S'ybll recounted her history to the Rebel, he mustered enough strength to push her away and flee from her. Shocked by his willpower but maintaining a strong psychic link with Skywalker, S'ybll conjured another illusion from his mind. An illusion of Skywalker's greatest fear, Darth Vader, was summoned, driving him back into her clutches. However, Skywalker resisted the illusion, and the vision of Darth Vader's attacks passed harmlessly through him. Refusing to concede defeat, S'ybll decided to eliminate the young man, planning to drain Skywalker's friends after dealing with him. Using her telekinetic powers, she collapsed nearby ruins onto her foe.
Believing she had crushed Skywalker, S'ybll sensed his friends nearby and called out to them, eager to drain their essences now that Skywalker was gone. However, Skywalker had evaded the attack and taunted the mind-witch. Enraged, S'ybll lashed out, throwing loose stones and broken ruins at the young man. The intense telekinetic assault drained S'ybll's energy, exhausting her. Severely weakened, the mind-witch's psychic hold on Skywalker was broken, and she collapsed among the rubble she had created. Knowing she was extremely vulnerable in her weakened state, S'ybll mustered just enough strength to conjure an image of her corpse pinned beneath a rock. Convinced S'ybll was dead, Skywalker, free from her power, left the planet with his friends.

After the Rebels departed her world, the mind-witch recovered from the battle. During her recuperation, Imperials arrived at Seidhkona searching for their lost shuttle. Instead of draining all the Imperials as before, she eliminated one of them and took his place, disguising herself with an illusion. Unable to determine the cause of their comrade's death, the Imperial group left Seidhkona and returned to an Imperial outpost on the planet Tarnoonga. The base housed the same stone columns that she had used on Seidhkona to amplify her powers, giving her an advantage over the Imperials. As she had done years ago, S'ybll began to drain the Imperials at the outpost of their life energy. The base also housed an Oskan blood eater, which S'ybll adopted as her pet. After replenishing herself, she made the outpost her home, concealing the dead stormtrooper's armor and bones in cargo containers. Rather than seeking revenge on Skywalker, S'ybll was impressed by his abilities and decided to persuade him to join her so she could use him to acquire Imperial victims. Sometime later, S'ybll's opportunity to contact Skywalker arose. Two Rebel scouts, Andur Thorsim and Glaennor, arrived on Tarnoonga in a G9 Rigger freighter to investigate reports about the Imperial base. Using her illusions, S'ybll tricked the scouts into believing they were being attacked by an Oskan blood eater. As the illusions drew the scouts closer, she showed them an image of a Jedi woman defeating the blood eater with her lightsaber. The Rebel scouts relayed the news of a Jedi to Alliance Command, who then forwarded the information to Luke Skywalker. With her plan in motion, S'ybll imprisoned the Rebel scouts and awaited Skywalker's arrival.
Hoping to connect with another Jedi, Skywalker traveled to Tarnoonga. After landing his X-wing next to the G9 freighter, Skywalker searched the area for the Rebel scouts. Upon Skywalker's arrival, S'ybll reestablished her psychic bond with him, pulling images from his mind to manipulate him. Using the image of Frija Torlock from Skywalker's past, she confronted him while creating further illusions of attacking blood eaters. Skywalker was shocked to see Frija and was convinced by S'ybll's story that Frija had become a Rebel scout. When Skywalker inquired about the Jedi woman he had come to investigate, S'ybll told him she had been killed by the blood eaters. Skywalker was unconvinced and began to sense the deception despite S'ybll conjuring more illusions. Although she made one last attempt to convince him by showing an image of Frija being attacked by a blood eater, Skywalker had discerned S'ybll's presence, seeing through the charade.
Although Skywalker assumed S'ybll wanted revenge, the mind-witch instead offered an alliance. Skywalker was disgusted by the idea, and even when S'ybll threatened to have her blood eater kill the Rebel scouts, Skywalker refused. Upon his refusal, S'ybll released her blood eater, which attacked the two scouts. Skywalker immediately jumped into the pit with his lightsaber to defend his compatriots. Using her illusions, she attempted to help her beast defeat Skywalker, but his skills were too great, and he quickly killed the blood eater. Defeated, S'ybll opened a hatch in the pit, flooding the chamber with water, and then sealed the pit with a blast door. However, Skywalker cut a hole in the trap, helping the scouts escape the rising water. Unwilling to admit defeat, S'ybll conjured more illusions, but Skywalker helped Glaennor and Thorsim see through them.
Forced to use her telekinetic powers, S'ybll threw stones at the Rebels, but Skywalker defended them. As the mind-witch increased the intensity of her attack, Skywalker noticed that the base contained the same stone columns he had seen on Seidhkona. Realizing the columns were amplifying S'ybll's powers, he used his lightsaber to cut through them, to S'ybll's horror. Out of options, S'ybll lunged at Skywalker and tackled him to the floor, intending to drain his life force as quickly as possible. However, the attempt was interrupted by the roof of the base exploding in a hail of blaster fire. Skywalker's droid, R2-D2, piloting the Rebel's X-wing starfighter, had used it to create a hole in the base after determining his master was in danger.
In the confusion, S'ybll lost her grip on Skywalker, who rolled away. Refusing to give up, S'ybll dove at her prey in one last desperate attempt. However, Skywalker used the Force to pull his lightsaber, which he had lost in the melee, into his grasp. Igniting the weapon just as S'ybll lunged towards him, the Rebel drove the blade through her chest. As Skywalker deactivated the weapon, S'ybll spoke her final words to the would-be Jedi and fell to the floor, dead.
Despite killing S'ybll with his own weapon, Skywalker remained uncertain. He commanded R2-D2 to land the X-wing and enter the base. After the astromech droid confirmed with his sensors that S'ybll was truly dead, Skywalker finally believed she was gone. With her death, Skywalker believed the last of the mind-witches had perished.

As a mind-witch, S'ybll possessed an extraordinarily long lifespan and inherent psychic abilities that allowed her to read thoughts and create illusions in her victims' minds. She could use these powers to establish a psychic link between herself and her victims. After forging this link, S'ybll could gradually drain the life energy from her victims. This process replenished her own energy, allowing her to regain a youthful appearance. S'ybll believed that draining the life forces of more powerful individuals, such as Luke Skywalker, could amplify her own power.
S'ybll also possessed powerful telekinetic abilities. During her battle with Skywalker, she toppled large stone structures and hurled rubble through the air at her enemy. The stone columns in her home augmented S'ybll's telekinetic powers, granting her greater control over the environment. When these columns were destroyed, her powers diminished. S'ybll's telekinesis had limitations, and overuse of her powers could significantly weaken her. During her attack on Seidhkona, she overexerted herself, causing her to collapse in exhaustion.

In her natural state, S'ybll had a withered, wrinkled appearance. Her skin was covered in warts, and her hair was long and white. After ages spent on Seidhkona, her hair was filthy, and her yellowed teeth guarded terrible-smelling breath. She had a bony frame with long fingernails and was very skinny. She wore clothing made from animal skins and maintained this appearance despite having access to other materials. However, after draining individuals of their life energy, S'ybll transformed into a youthful form with smooth skin and long red hair. S'ybll enjoyed appearing youthful and sought to drain individuals to maintain this appearance. S'ybll kept the bodies of her victims after draining them of their life force. She used the skull of one of her victims as a candle and, after eliminating the Imperial force on Tarnoonga, she stored the bodies in cargo containers.
S'ybll was a long-lived individual who resided on the planet Seidhkona for countless years before encountering the Imperials. She was a cruel and selfish individual who felt no remorse about draining and killing others to maintain her youth. After encountering Luke Skywalker, she hoped to form an alliance with him so he would provide her with more victims to drain. Upon his refusal, she became enraged. S'ybll possessed a dangerous pride and enjoyed the enhanced abilities granted by the stone columns on Seidhkona and Tarnoonga. The mind-witch was afraid to be away from these structures which granted her enhanced power, which is why she had spent such a long time on Seidhkona and had sought out the same type of structure on Tarnoonga. Skywalker exploited S'ybll's pride during both of their encounters, tricking her into exhausting her powers in an attempt to destroy the defiant Rebel.
S'ybll was conceived by Archie Goodwin and brought to life by Al Williamson for the Star Wars comic strip story The Paradise Detour, published by the Los Angeles Times Syndicate. Dark Horse Comics later reprinted this story in Classic Star Wars 17 and 18. These reprints colored the original black-and-white comic strip panels and reorganized some of the comic panels, removing redundant parts of the storyline. S'ybll was later mentioned in the article ComicScan: Star Wars...On A Daily Basis in issue 2 of Star Wars Galaxy Magazine, which recognized her as an original creation of the comic strip. Two subsequent articles in Star Wars Galaxy Collector magazine also discussed S'ybll's exploits in the comic strip. ComicScan: Coming Full Circle in issue 3 referenced the storyline S'ybll was involved in, and ComicScan: Luke-ing for Love in all the Wrong Places in issue 7 mentioned Skywalker's brief attraction to S'ybll.

Although S'ybll seemed to die at the conclusion of The Paradise Detour, she reappeared in the book A New Hope: The Life of Luke Skywalker, which revealed her survival after the fight with Luke Skywalker. Penned by Ryder Windham, the book was dedicated to the memory of Archie Goodwin and included a written adaptation of The Paradise Detour and a conclusion to S'ybll's narrative. The mind-witches, S'ybll's species, were given an entry in The Complete Star Wars Encyclopedia, and she also received an entry in A Guide to the Star Wars Universe, Second Edition, Revised and Expanded. The Essential Reader's Companion summarized The Life of Luke Skywalker and identified the planet in The Paradise Detour as Seidhkona, a detail not present in the original comic. S'ybll was noted as the first appearance of witches in the Star Wars universe in Everything You Always Wanted to Know about the Nightsisters but Were Afraid to Ask, an article in Star Wars Insider 122.
The Essential Reader's Companion identifies S'ybll as a Human female belonging to the mind-witch order. However, The Complete Star Wars Encyclopedia classifies "mind-witches" as a distinct humanoid species.