Rebel Alliance Wikia

Galen Marek was a Jedi Knight and helped found the Alliance to Restore the Republic alongside Jedi Master Rahm Kota, Bail Organa, Mon Mothma, and Gam Bel Iblis. Originally the Sith padawan to Darth Vader, Marek under the nickname, Starkiller, would later betray his master and save the leaders of the Rebellion aboard the Death Star. Years later, Marek would later be cloned by Vader, but the clone, still having the memories of original Starkiller, would betray Vader and rejoin the Rebel Alliance in a attack on the planet Kamino.