A select few knew Palpatine was Darth Sidious, including his apprentices Darth Maul and Count Dooku, his advisors Mas Amedda and Sly Moore, and eventually the Jedi Council (Yoda, Mace Windu) and Anakin Skywalker, while some high-ranking Imperials like Tarkin and Thrawn suspected or knew he was a powerful Force user but not necessarily Sith. Others like the Knights of Ren and Ghost Crew learned the truth later, but most citizens and Imperials remained unaware of the Sith Lord ruling behind the Chancellor's mask.
Were his parents Sith, and did they hide Palpy from the Jedi? This might explain a lot. If he's a senator it's reasonable to assume he comes from wealth and could have had private tutoring in his early life, keeping him segregated from others whom he might be tempted to show off his force powers to.
Seems pretty easy to deduce for Ahsoka. She knew there was a dark Lord of the sith who had control of the Senate. Palpatine was disfigured after an attack by the Jedi.
It's difficult to say whether or not any of the Rebel leaders knew Palpatine was a Sith Lord. Although Bail Organa heard Yoda and Obi-Wan talking after their fateful battles with Darth Sidious and Darth Vader, he was never actually told.
In Legends, Thrawn had worked with Sidious on the destruction of the Outbound Flight project. The next time they met was decades later, and Sidious had become Emperor. Thrawn probably figured out the Sidious-Palpatine connection right away, and I doubt Sidious would've bothered hiding it.
Plagueis was fully aware Sidious was training Maul as a Sith assassin. Plagueis knew about Maul, Maul suspected Sidious had another master but didn't know for sure. Plagueis had actually intended to end the rule of two with himself and bring back the Sith numbers so he encouraged Sidious.
Darth Maul is the weakest. Bane was strong : he killed all the Sith and lots of Jedi.
Likely unaware of his true nature, Snoke was an artificial genetic strandcast created on the planet Exegol by the resurgent Dark Lord of the Sith and Galactic Emperor Darth Sidious as a proxy and the product of cloning experiments.
He may have been worried about revenge. An alternate theory would be that he just didn't know. Palpatine kept his true identity very secret. He probably only revealed it to Dooku to better lure him to the dark side.
Though there was some debate among the fans that Anakin Skywalker's son, Luke Skywalker, was actually the Chosen One since he caused his father to destroy Darth Sidious, the debate was settled when George Lucas himself confirmed in an interview that Anakin, even after becoming Darth Vader, was still officially the ...
During the staged kidnapping of Palpatine, orchestrated by Sidious himself, Grievous was unaware of Palpatine's true identity. In fact, Grievous was prepared to kill the Chancellor if necessary, despite his orders not to, believing that Sidious would forgive him due to the ongoing war.
In 52 BBY Dooku accompanied Jedi Councilor Jocasta Nu, his friend Sifo-Dyas and his former apprentice Qui-Gon Jinn on a mission to his home world of Serenno to resolve a dispute in the sector. While there, he met the Muun Hego Damask, in reality the Sith Lord Darth Plagueis.
I genuinely believe ahsoka was one of yoda's favourite Jedi ever!!!
During the High Republic Era, Plagueis was actively working against the Jedi. By 132 BBY, he had taken on a former Jedi—a human known as "the Stranger" or by the pseudonym "Qimir"—as his apprentice.
As a result, Lucas created the fan-favorite character of Darth Maul, who was introduced in the first prequel trilogy film. However, Maul was killed off unceremoniously at the end of the film. Nonetheless, Lucas eventually regretted the decision to kill off such a beloved and fascinating character.
If you remember from The Clone Wars, though, as soon as Sidious sensed Ventress growing stronger, he suspected that Dooku was training her as his apprentice and ordered her to be destroyed.
But I'll tell you the one person Palpatine genuinely feared more than Yoda or Windu: That's right: Qui-Gon Jinn. Qui-Gon was a follower of the Force, not just the Jedi, and he was often at-odds with the rulings or decisions of the Council.
Qimir has already been calling himself Darth Venamis, and is ready to officially be a Sith Lord Apprentice, but, is also already conspiring to get a pupil of his own, & eventually kill his own master as well.
Matthew J Meyer George Lucas has stated: "Anakin Skywalker was conceived by the midi-chlorians, but it was Palpatine who manipulated the midi-chlorians to create Anakin" (Source: "Star Wars: Episode III - Revenge of the Sith" DVD commentary, 2005).