Galen Marek, codenamed Starkiller, was a male Human apprentice of the Sith Lord, Darth Vader. He was an extremely powerful Force-wielder who lived during the era of the Galactic Empire. He was a playable character in the Sith Temple Game and was played by Li.
The Sith Temple Game[]
In the Sith Temple Game, Li (Starkiller) had the role of murderer, this was put to good use on the Sith vs Jedi day, with Li killing Darth Vader, by removing the Sith Lord's burnt helmet.
Later on the Return of the Jedi day, after Plageuis died, Starkiller killed Darth Maul by cutting him in half.
On the One out of Four day, it was Dooku who exposed Marek's true colours. Starkiller was killed by Sidious. After his identitiy was revealed.