Is Darth Sidious two people? I heard that Darth Vader killed Darth Sidious, but Darth Sidious comes back in The Rise of Skywalker. Also, there is another emperor in The Last Jedi, but who is he? Is he also Darth Sidious? If so, how did he survive after Rey chopped him in half in The Last Jedi?
Darth Sidious is the name used by the Emperor of the Galactic Empire, Sheev Palpatine, in his dealings as a dark lord of the Sith. He was killed during the events of Return of the Jedi by Darth Vader when he was flung down a shaft on the second Death Star. However, just before his death he used the power of the dark side of the Force to transfer his consciousness into a cloned body, which is the version of the character that appears in The Rise of Skywalker. The "emperor" in The Force Awakens and The Last Jedi is a different character named Supreme Leader Snoke, who served a similar role as leader of the First Order, but was not the same person.