George Lucas created the possibility that Palpatine survived the events of Star Wars: Return of the Jedi, setting up his potential return in Star Wars: The Rise of Skywalker, but nobody even noticed. The Star Wars prequels have seen a lot of criticism over the years, including the repeated suggestion that movie prequels are inherently flawed because they can't amount to much more than a checklist of events leading to the story we already know, but that's not true when it comes to a major moment in Star Wars: Revenge of the Sith.
Widely regarded as possibly the best scene in the prequel trilogy, and popular as a meme in its own right, Palpatine telling the story of the Tragedy of Darth Plagueis the Wise to Anakin didn't just serve to tempt his future apprentice, it also created that glaring possibility that Palpatine was capable of surviving the end of Return of the Jedi.
The notion of Palpatine surviving his battle with Luke (and the betrayal of Darth Vader) is hardly new to Star Wars. The Dark Empire comics in the early 90s told a story about a resurrected Palpatine who could transfer his consciousness into one of many clones he had waiting around just for that purpose. While Lucas often had little to do with Expanded Universe stories, he was supposedly so pleased with that particular story that he gave it out as his annual holiday gift to Lucasfilm employees.
So, when it came time for the prequels, a decade and a half later, it should have sent off alarm bells when Palpatine infers to Anakin that his master, Darth Plagueis, knew how to prevent people from dying, and taught Palpatine the ability before his apprentice killed him. Then, likewise, when it came time for the sequel trilogy, fan theories about Darth Plagueis being involved were common, but the much more logical assumption, that Palpatine survived, wasn't nearly as common as maybe it should have been in retrospect.
Palpatine's master wasn't able to save himself, apparently because Palpatine killed him in his sleep, but Vader's master was wide awake when he threw him down the reactor shaft of the second Death Star. At the time, the idea of Darth Sidious living on after his apparent death may not have seemed shocking since it was still considered canon as a part of the Expanded Universe, but since the Disney purchase of Lucasfilm when the Expanded Universe became non-canon "Legends," it still should have been a big question of whether or not Palpatine still lived.
Now that his presence in Star Wars: The Rise of Skywalker has been confirmed, a quick look back at the Darth Plagueis scene in Star Wars: Revenge of the Sith and a number of other current canon stories written since the Expanded Universe was abandoned teasing Palpatine's quest for immortality, it's actually clear as day that Palpatine's story wasn't over yet.
- Star Wars 9 / Star Wars: The Rise of Skywalker (2019) release date: Dec 20, 2019