The Dark Apprentice, who was also called "Starkiller," represented a clone of Galen Marek. Galen Marek was a Force-sensitive Human male whom the Sith Lord Darth Vader took as his clandestine apprentice, with the same codename "Starkiller". After Marek's death, Vader set out to engineer a flawless, obedient replica of him, intending for the clone to assume Marek's former role. Within the cloning facilities located on Kamino, numerous unsuccessful attempts preceded the Dark Lord of the Sith's eventual success in creating a clone of his late apprentice. This clone managed to overcome the original template's emotional responses and completely dedicate himself to the dark side of the Force.
As his training advanced, the Dark Apprentice outstripped all prior attempts; he gained the capability to retain Marek's memories separately from his own and to suppress the deceased man's emotions. Vader's scheme involved the apprentice undergoing a final trial against a renegade Marek clone amidst the Rebel attack that occurred on Kamino. However, the Dark Apprentice abstained from participating in the battle, and his Sith Master was captured by the Alliance to Restore the Republic.
The Dark Apprentice was created on the ocean-dominated planet of Kamino around the year 1 BBY. He was a clone derived from Galen Marek, who was the deceased apprentice serving the Sith Lord Darth Vader. His creation was part of Vader's initiative to develop a perfect and submissive replacement for Marek. Before him, several clones were produced, all of whom underwent training using memory flashes taken from the original Marek's experiences. These predecessors did not fulfill the required standards for various reasons, including genetic flaws or succumbing to the emotions of their template, leading to their rejection.
Upon his awakening, under Vader's supervision, the Dark Apprentice faced Marek's memories, notably the man's feelings for his former pilot, Imperial-turned-Rebel Captain Juno Eclipse. He immediately questioned her location, but Vader dismissed her as irrelevant, emphasizing the importance of the task at hand. Nevertheless, the Dark Apprentice persisted in inquiring about Marek's identity in the future. Vader consistently avoided direct answers, stating instead that the clone had inherited the memories, thoughts, and dreams of a broken individual, far weaker than the Dark Apprentice. As a consequence of the cloning procedure, he carried both the strengths and weaknesses of his genetic source.
The Dark Apprentice underwent training in lightsaber combat against several Sith Training Droids. After observing his advancement, Vader presented him with the cloning platforms within Timira City's clone spire, showcasing all his rejected predecessors held in stasis. The clone resolved to surpass all others, but he was curious about the number of those who had come before him. Vader ignored the question, informing the Dark Apprentice that the only relevant number was the quantity of clones that would be needed if he failed like the others. Vader cautioned that failure to overcome Marek's emotions would result in the same fate as his predecessors.
Over time, the lead cloning technician noticed that the Dark Apprentice could isolate the memory imprints employed in his training, achieving what all others had failed to do. The clone could store Marek's memories separately from his own, thereby freeing himself from his template's emotions.
With the apprentice now unburdened by Marek's memories, Vader led him to a chamber housing his template's lifeless body. The clone grasped the significance of this gesture, and his Master believed that he, unlike all those before him, would prove successful. In a training exercise against holodroids, the Dark Apprentice transcended Marek's emotions, striking down a droid that resembled Captain Eclipse. The clone expressed to Vader his disgust and hatred for his template's weaknesses, along with his pride in overcoming them where others had failed. Satisfied, Vader declared that he was nearly prepared for his final test.
During the culminating stages of the Dark Apprentice's training, a rogue clone of Marek, who had previously escaped Kamino, allied with the Rebel Alliance in an attack on Timira City's cloning facilities. Vader intended to exploit the battle as the Dark Apprentice's final trial, luring Starkiller into a trap at the cloning spire's summit.
Before departing to confront Starkiller, Vader instructed the Dark Apprentice to await his call for assistance. The apprentice affirmed his readiness to fulfill his purpose. However, the trap deviated from the plan. Starkiller defeated Vader in a lightsaber duel but refused to deliver the killing blow, having foreseen in a vision that he would be slain by Vader's new apprentice—the reborn Starkiller—if he attempted to kill his opponent. The Sith Lord was captured by the Alliance at the conclusion of the battle, without any intervention from the Dark Apprentice.
Distinct from the clones preceding him, the Dark Apprentice successfully suppressed Galen Marek's emotions, marking him as the sole success in a project riddled with failures. To the delight of the lead clone technician monitoring his progress, the apprentice managed to isolate the original Marek's memories, enabling the clone to differentiate between his own thoughts and those of his genetic template. The Dark Apprentice developed a deep contempt for his template's emotions and shortcomings, ultimately taking pride in surpassing the weaknesses that had hindered his predecessors.
Having been created from the genetic blueprint of Darth Vader's former apprentice, the Dark Apprentice inherited the same abilities and Force potential as his progenitor. During his training on Kamino, the Dark Apprentice received instruction in lightsaber combat against numerous Sith training droids, employing the dual blade combat style known as Jar'Kai. As the clone's training advanced, Vader informed the Dark Apprentice that he had surpassed the original Starkiller in power within the Force. By the time of the Rebel attack on Kamino, the Dark Apprentice's profound immersion in the dark side of the Force manifested physically, causing his skin to pale and his irises to turn red.
The Dark Apprentice, also known as the "reborn" Starkiller, made his initial appearance in The Force Unleashed II novelization within a vision aligning with the non-canon dark side ending of Star Wars: The Force Unleashed II. In addition to the video game's Databank section, the dark clone's origins were elaborated upon in a series of cutscenes titled "Distant Thunder," which are bonus features unlockable by completing various challenges in the game. Sam Witwer lent his voice to the Dark Apprentice in these video clips. Given that these cutscenes do not affect the game's progression and chronologically precede the player's choice between the canonical and non-canonical endings, it is generally assumed that the Dark Apprentice is considered canon, even though he does not appear in the light side ending of the game. This assumption is largely based on the fact that, in the novelization of the game, Starkiller experiences a vision in which he attempts to kill Vader at the end of their duel, only to be killed by the Dark Apprentice. This revelation significantly influences his decision to spare Vader's life. This vision also aligns with the content presented in the "Distant Thunder" extras and the events of the non-canon dark side ending. The Dark Apprentice is further featured in downloadable extra content for The Force Unleashed II, which includes a non-canon bonus mission that follows the dark side ending of the game.
In the non-canonical dark side ending of The Force Unleashed II, the player, assuming the role of Galen Marek's clone, opts to strike down Darth Vader. However, before this can occur, a lightsaber pierces the clone's chest. A cloaked figure, having used a cloaking device to approach undetected, is revealed as the blade's wielder. He proceeds to defeat Jedi General Rahm Kota in a brief duel before using the Force-choke ability on the General and pushing him and several Rebel troopers into the ocean below, while Terror Troopers handle the remaining Rebel soldiers. Vader approaches the dying clone of Marek, revealing that he had lied about the cloning project's failure as the hooded figure reveals himself to be the Dark Apprentice, Galen Marek's perfect clone, whose immersion in the dark side is physically manifested through his pale skin and yellow eyes.
With the Rebel assault thwarted, Vader praises his new assassin for completing his final challenge. The obedient clone kneels before Vader, who assigns him the task of using the Rogue Shadow to locate and eliminate the surviving Rebels scattered throughout the galaxy. As he departs, the Dark Apprentice briefly glances at the lifeless body of Juno Eclipse, feeling no emotions for her. He then raises his hood and continues on his mission. Accompanied by a squadron of TIE fighters, the Dark Apprentice departs Kamino in the Rogue Shadow and enters hyperspace to fulfill his orders.
In downloadable content, the Dark Apprentice takes part in an alternate depiction of the Battle of Endor. The surviving members of the Rebel Alliance launch an attack on the second Death Star orbiting the Forest Moon of Endor, overcoming Imperial forces and gaining access to the shield generator bunker with the aid of the native Ewoks. Darth Vader sends the Dark Apprentice to the moon to address the threat, while Vader remains with Emperor Palpatine aboard the new battle station. After landing the Rogue Shadow on Endor, the Dark Apprentice battles through Rebel soldiers and Ewoks on his way to the bunker, destroying the Alliance's shuttle in the process. At the base, the apprentice is confronted by smugglers Han Solo and Chewbacca, with the latter piloting an AT-ST to guard the bunker's entrance. The clone eliminates the duo before entering the bunker, where he proceeds to kill both Rebels and Imperials.
Inside the bunker, the Dark Apprentice encounters Leia Organa, the Alderaanian princess who became a Jedi following her twin brother's death on Hoth. The two engage in a duel, with Organa attempting to use the facility's machinery against her opponent. The apprentice repeatedly gains the upper hand, forcing the fight to continue on the bunker's roof. Despite being impressed by Organa's skills, the dark clone's own abilities allow him to overpower and kill the female Jedi. Aboard the Death Star, the Emperor celebrates the Imperial victory before revealing to Vader that he was aware of the Dark Apprentice's existence. Referring to his treacherous apprentice as "Skywalker," Palpatine threatens to kill Vader for conspiring to overthrow him. Vader ignites his lightsaber in an attempt to strike down his Master, but Palpatine forces him to his knees with a barrage of Force lightning. He then orders Captain Sarkli to deploy his forces and eliminate the apprentice on Endor. As the dark clone meditates near Organa's body, he senses the arrival of several Star Destroyers and opens his eyes.