Sasori Vader existed as a changeling being during the Galactic Civil War, making its home inside a Jawa sandcrawler situated on the planet of Tatooine. While its authentic form manifested as a colossal scorpion distinguished by intensely red, luminous eyes, it possessed the capacity to morph into the likeness of the Sith Lord Darth Vader.
In the year 0 BBY, Sasori Vader, having somehow commandeered a Jawa sandcrawler, took two Jawas captive (these Jawas had themselves previously captured R2-D2), confining them within the control center of their erstwhile transport. Subsequently, the young Luke Skywalker journeyed to the sandcrawler with the intention of liberating his droid companion and confronting Sasori Vader, who had assumed the guise of Darth Vader. During the ensuing conflict, Sasori Vader reverted to its original scorpion form; however, Skywalker ultimately triumphed, resulting in the creature's demise.
Sasori Vader appeared as one of the boss characters in the Japanese Star Wars 1987 video game. This particular game showcased various imposters of Vader, each revealed to be shape-shifting monsters. The canonicity of both the game itself and the creatures featured within remains questionable.
According to both the article "Game On!," featured in Star Wars Insider 135, and the game's instruction manual, the false Vaders (Clados, Gyaos, Sasori, and Wampa) were "conceived as illusions that embody Luke's inner fears, akin to the Cave of Evil sequence in Empire Strikes Back." Nevertheless, given that these adversaries managed to abduct Luke Skywalker's allies and hold them as prisoners, this analysis posits that they were actual entities rather than mere figments of imagination. Moreover, the Vader-esque figure encountered by Skywalker in the Cave of Evil transcended a simple illusion, functioning as a protean dark side entity recognized as the Dark Spirit.
Within the game and its original Japanese language manual, the character is designated as Sasori Beidā (サソリベイダー). While Beidā represents a Japanese transliteration of "Vader," Sasori translates directly to "scorpion."