Count Dooku - himself revealed to be a Sith Lord - revealed to the captured Jedi Knight Obi-Wan Kenobi on Geonosis in 22 BBY that a Sith named Darth Sidious held influence over several senators in the Galactic Senate; it was the first such time that the Jedi learnt about Sidious in name.
The Jedi didn't find Palpatine for a very good reason, and his master, Darth Plagueis, only found him by chance. While plotting to force Naboo onto an expanding galactic stage because of a plasma reserve, Plagueis decided to use a Naboo nobleman's son – who had already leaked damning information once – as a spy.
Very close. In the book Labyrinth of Evil, Mace Windu and his group of Jedi track darth sidious down to the 500 republica building.
Precious few people in the Star Wars galaxy knew Palpatine was actually a Dark Lord of the Sith - here's a complete list. The Emperor carefully concealed the fact he was a Sith Lord - even when he ruled the entire Star Wars galaxy.
Force Clouding was a Force technique used by the Sith, particularly those who belonged to the Order of the Sith Lords to mask their Dark side powers when in the presence of the Jedi.
DARK SIDE FRIDAY - Did you know Palpatine feared Qui-Gon Jinn? Palpatine was immensely powerful and he could see the future which made him very confident about pretty much anyone who stood against him.
It was like the perfect storm: Palpatine's strong dark side powers and the shrine's energies blocked the Jedi Order from seeing the truth as Palpatine plotted their destruction right in front of them.
In fact, in this same scene, Sidious says he is keeping Maul alive because he has "other uses for you!" If Palpatine thought Maul knew he about his double identity, there's no way he would have let him stay alive.
Amedda was one of the few in the galaxy who knew Palpatine was a Sith Lord, and assisted the Chancellor as Speaker of the Senate, helping him manipulate Senators into granting him more and more power.
Sidious used Plagueis' methods to transfer his consciousness to a new body after his first demise. During the Battle of Endor in 4 ABY, Sidious was killed by a redeemed Anakin Skywalker, who turned back to the light side of the Force and threw Sidious down a reactor shaft to save his son Luke Skywalker.
The two veterans of the Force engaged in a ferocious lightsaber duel, with each making liberal use of their powers. Ultimately, Yoda was forced to flee after coming to the conclusion that he could not possibly defeat Sidious, despite his great ability.
Unfortunately for the galaxy, as Palpatine grew in power the shroud of the dark side fell over the galaxy, diminishing the Jedi's ability to sense the Force. Thus Yoda failed to realize how close to home the Sith really were - until it was far too late.
In the film fight, we never actually see Sidious lose his lightsaber—he simply switches to a Force-based assault. But according to the official Star Wars Wookiepedia, Yoda did in fact overpower and disarm Sidious in their blade contest, forcing the Sith to change tactics.
As the first Dark Lord of the Sith, Ajunta Pall founded the first Sith Empire and expanded it onto other worlds. The Sith took over the planet Ziost and created it as their capital and as Pall's new home. Pall eventually died after serving the Empire for many decades, but his Empire lived on.
The young aristocrat was so adept at hiding his presence in the Force that even the experienced Dark Lord couldn't detect his power. Palpatine wished to join the Sith and his astounding aptitude for both the dark side of the Force and the ability to mask his true power resulted in the Jedi never discovering him.
Most fans agree that he probably wasn't ever a Jedi because of the way the Jedi Order works. If he had been a Jedi, he would have been brought to the Jedi temple on Coruscant as a youngling and trained there until he became a Padawan.
Despite this ambition, Pestage was one of Palpatine's closest and most loyal servants, and was said to be one of the few people who truly knew him. He was entirely loyal and dedicated to his master, and Palpatine considered him to be the most trusted of his advisors and a good friend.
A Sith Lord with the ability to prevent death and create life, Plagueis is the mentor of Sheev Palpatine/Darth Sidious, who, in accordance to the Sith's Rule of Two, eventually betrays Plagueis by murdering him in his sleep, taking his place as Sith Master.
How Count Dooku Planned to Betray Palpatine Before Star Wars: Revenge of the Sith. For his short time as a Sith, Count Dooku was well aware of Star Wars' Rule of Two. In fact, he even planned on replacing Palpatine before Order 66.
In 2017, Marvel released Star Wars: Darth Maul, a 5-issue prequel series centered on Maul before the events of The Phantom Menace. The comic details upon Maul's training under Darth Sidious, and how he was manipulated into hating the Jedi for leading the Sith to near-extinction.
Despite learning that his Master took a new apprentice, Darth Tyranus, Maul still believed that he was a Sith Lord. Taking his brother as an apprentice, Maul and Opress held that they were the true Sith rather than Sidious and Tyranus.
We see this when Dooku confronts Obi-Wan and asks him for help destroying the Sith. He's telling the truth. He does want to destroy the Sith, he just wants to destroy the Jedi as well and enforce a government tailored to his particular ideals.
In addition to his self-centered and manipulative nature, Palpatine exhibits psychopathy: the inability of a person to properly feel emotion. Throughout the Star Wars franchise, the Emperor feels no empathy for anyone.
In The Rise of Skywalker's novelization, written by Rae Carson, it's revealed that Rey's father is a failed Palpatine clone. He was initially created as a vessel to house the Sith Lord but proved incapable of doing so.
Palpatine chose to keep his face as a symbol of the Jedi's treachery and as a way to appear weak to his enemies. The Sith Lord's rise to power based itself on appearing weaker than he actually was, and he continued that until his death.