As powerful as Darth Sidious may have been, it's easy to forget he actually seemed afraid of Master Yoda. As seen in Revenge of the Sith, Palpatine initially thought he could deal with the aged Jedi Master - and then, when Yoda proved able to counter the Sith Lord's Force lightning, he fled.
The first Sith Lord Yoda actually encountered was his former pupil, Count Dooku, but this happened during Attack of the Clones.
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.
Whether it was Palpatine, or Darth Vader, or Count Dooku, everybody has their favorite Sith Lord who displayed its chilling power in full force. Whoever your favorite Sith may be, however, they all have one fear in common: Themselves.
1 Darth Sidious
There has been no Sith, as powerful, meticulous, nor as evil as the Emperor himself, Darth Sidious. As previously mentioned, Sidious trained in the Dark Side by Darth Plagueis before Sidious killed Plagueis in his sleep, making Sidious a Sith Master.
Yoda's Duel With Palpatine Called for a Strategic Shake-Up
Yoda claims that the light side of the Force is stronger than the dark, but his battle against Palpatine is almost equal. The Sith Lord's powers were enough to overwhelm the Jedi and send him plummeting down to the depths of the senate chamber.
Yoda didn't specifically know how this would go down, or to what degree Anakin would cause it to happen, but he was playing a much longer game by Revenge of the Sith, and that's at least, in part, explained by Yoda's Force connection with Qui-Gon's spirit.
This ensured that the Sith could hone their skills in secret without fear of betrayal from rival Sith factions. More cunning and devious than all but the most attuned Force-sensitive beings, Darth Bane could more than likely defeat Yoda in a battle of both strength and wit.
Jedi like Luke Skywalker and Obi-Wan Kenobi have long stood as light against the darkness. But the record Sith-killer is actually Darth Bane himself. Darth Bane, founder of the Rule of Two, killed more Sith than any Jedi in the history of the Star Wars galaxy.
Yoda never killed a Sith Lord, either in canon or in Legends. This is mainly due to the fact that there are so few Sith Lords due to the Rule of Two. The following is the complete canon list of known Sith Lords alive during Yoda's lifetime: Darth Plagueis (murdered by his apprentice, Darth Sidious)
As powerful as Darth Sidious may have been, it's easy to forget he actually seemed afraid of Master Yoda.
Palpatine admits to Darth Vader that the Jedi he actually feared most was none other than Jocasta Nu.
And while Yoda and Palpatine both worked with the Senate, they treated each other with the utmost respect. While Palpatine plotted in the shadows and planned his Galactic Empire, he underestimated Yoda. And even when Yoda discovered Palpatine's true nature, Yoda underestimated his power.
One of the main reasons why Yoda would've won against Anakin is simply because he was far better trained than him. Yoda could see the moves his opponents were going to make before they made them; therefore, battling against Anakin would've put him at a far heavier advantage.
aware that Anakin had become the Sith Lord Darth Vader. Qui gon felt responsible because it was his dying wish. that Anakin betrayed in the ways of the Force. As the years went by, Qui Gon pushed himself to emerge physically as a spirit.
Ultimately, Yoda gained a new understanding of true selflessness and of the Force, came to realize his hubris and the mistake the Jedi Order committed by becoming warriors, and unlocked the secret of Force immortality. As the Clone Wars raged on, Anakin and Obi-Wan had become heroes of the Republic.
If Qui-Gon had survived his fight against Darth Maul, he would have sensed Palpatine's evil, and Anakin wouldn't have become Darth Vader. Thus, while Qui-Gon was less powerful than Yoda, Palpatine feared him more.
Master Yoda failed Anakin Skywalker in Star Wars: Episode II — Attack of the Clones, and it resulted in the destruction of the Jedi Order. Master Yoda is one of the most revered characters in the Star Wars universe, and for good reason, but he ultimately failed in stopping the rise of the Sith.
1. Darth Sidious (Star Wars: Episode I – The Phantom Menace) Truly, the most powerful Sith Lord was Darth Sidious, better known in his public persona of Chancellor (later Emperor) Palpatine. Through cunning and manipulation, Sidious killed his master to claim the mantle of Dark Lord of the Sith.
Darth Vectivus was created by Aaron Allston for the first novel of the Star Wars: Legacy of the Force series, Legacy of the Force: Betrayal. He appeared as a spirit to Nelani Dinn and served as a platform for Lumiya to convince Jacen Solo to become Darth Caedus by showing him that not all Sith were necessarily evil.
That would most likely be Darth Vectivus. Unlike most Sith Lords, he wasn't interested in galactic conquest or exterminating the Jedi. He was a Force-sensitive businessman who simply happened upon the Dark Side and was fascinated by it.