The being known as The Imprisoned One was a Rakata who existed during the period when the Infinite Empire held sway over the galaxy. His ambition for supreme power led to his own people trapping his consciousness within a mind prison. This mental enclosure was later found on two separate occasions: initially by Revan during the time of the Jedi Civil War, and then, centuries afterward, by the Czerka Corporation during the era of the Cold War.
The Imprisoned One's life unfolded at the peak of the Infinite Empire's power. In spite of his species' many achievements that spanned the galaxy, he yearned to elevate his own status far beyond any other Rakata. In his efforts to use the Force alongside a form of nanotechnology to ensure his own everlasting life, his actions were quickly deemed criminal and heretical by his people. He was hunted down, and through now-lost technologies, his consciousness was extracted from his physical form and confined within a mechanical vessel. This vessel was then hidden deep within a cave, intended to serve as his permanent prison.
After the eventual collapse of the Infinite Empire, he remained dormant and forgotten within his prison for millennia. Eventually, during his second search for the Star Forge, he was rediscovered and interacted with by Revan, who opened the prison despite the warnings of Lurze Kesh.
The Imprisoned One possessed the knowledge of a ritual that could free another from the Rakatan Prison. He struck a bargain with Revan, the latest individual to enter his confinement. He proposed that if Revan could best him in a riddle game, he would be set free. However, should Revan fail, the prisoner would escape and take possession of Revan's body, condemning him to an eternity within the prison. After several riddles, Revan presented one that the Imprisoned One could not solve. The prisoner, forced to remain inside, reluctantly released Revan, aiding the hero in his quest for the Star Forge.
During the Cold War, three centuries later, a Czerka Corporation archaeological team once again discovered the Imprisoned One. He swiftly transformed them into mindless drones using the very nanotechnology he had once employed in his attempt to achieve immortality. The Czerka staff's emergency protocols successfully isolated the cave, preventing the further spread of the Imprisoned One's influence. However, the damage was irreversible: having faded into obscurity, the modern age was now aware of his existence once more.
Sometime after this, the Imprisoned One's influence managed to extend beyond his cave once again. This eventually attracted the attention of both the Imperial and Republic forces on Tatooine when several individuals became infected and turned against their colleagues.
The Imprisoned One made his debut in the video game Star Wars: Knights of the Old Republic. The riddle game he engages in with Revan appears to draw inspiration from chapter five of J.R.R. Tolkien's The Hobbit: Riddles In The Dark. Within this chapter, Bilbo Baggins, the titular Hobbit, participates in a riddle exchange with a creature named Gollum to avoid being devoured. Notably, one of the riddles posed by the Imprisoned One was originally used by Gollum in The Hobbit. This riddle was: "What has roots as nobody sees, is taller than trees, up, up it goes, and yet never grows?"
Following his appearance in Knights of the Old Republic, the Imprisoned One resurfaced in BioWare's 2011 massively multiplayer online role-playing game sequel, Star Wars: The Old Republic. The encounter with the Imprisoned One serves as the culmination of the Tatooine storyline for both the Republic and the Empire. Republic players have the option to destroy the mind prison, preventing the Imprisoned One's potential release (light side), or to hand it over to a rogue Czerka agent for exploitation (dark side). Similarly, Empire players can choose to destroy the mind prison (light side) or deliver it to the Imperial Reclamation Service for their own purposes (dark side).