Star Wars: Every Sith Who Turned To The Light Side

The action-adventure game, Star Wars: The Force Unleashed, begins with Darth Vader murdering two Jedi Knights on Kashyyyk, only to learn they had a Force-sensitive son called Galen Marek. Not only does Vader decide to spare the boy, he takes him on as his apprentice. After erasing Galen's memory and dubbing him 'Starkiller,' Vader begins training him in secret, hoping to use his power to overthrow The Emperor.

When The Emperor learned of Starkiller's existence, Vader was quick to turn against his student. Despite this betrayal, Starkiller remained loyal to his master and took steps to have The Emperor eliminated. After he encouraged the Senators, Bail Organa, Garm Iblis, and Mon Mothma, to join him in destroying The Empire, Vader's forces barged in and had the senators arrested.

Only when Vader betrayed him a second time did Starkiller truly realise his master only cared for himself. Rejecting the Dark Side, Galen infiltrated the Death Star and helped his allies escape. Even though he was killed in the process, his direct actions led to the senators forming the Rebel Alliance, which became a thorn in the Empire's side for decades.