Darth Plagueis was a Sith Lord who was rumoured to save the ones dear to him from death . He loved his apprentice like the son he never had . His apprentice was Darth Sidious aka Palpatine. He formed a plan in which he and Sidious would rule the galaxy as equals. Sidious however took a secret apprentice ,Darth Maul ,and killed his master in his sleep. He was to appear as a spirit and villain along fellow Sith and Imperial Overlord Darth Vader and would have been a boss. At one point he was alive and Vader would have sent Starkiller to find Plagueis , so Vader can bring his wife back from the dead. At another point Starkiller was a reincarnation of Plagueis ,but Plagueis was ultimately scrapped as the team thought that it would be difficult to bring the Sith Lord in the game. He was a human at one point as seen in some sketches and was later changed to a Muun in the last sketches , before being confirmed that his species was indeed the Muuns. In all sketches he has a Sith cloak.