1 Darth Sidious
As well as being a gifted bladesman Sidious' connection to the Dark Side is extremely powerful, granting Sidious the ability to conduct force lightning. Likewise, Sidious took on both Darth Maul and Darth Vader as his apprentice, two of the most powerful Sith and best villains in all of Star Wars.
Both Jedi Master Yaddle, and now Grogu hold great force powers, but no Jedi Master has ever held greater power than Jedi Master Yoda. Throughout Star Wars canon, Yoda has shown off some incredibly impressive abilities.
Alas, there can also be no denying that Darth Sidious, a.k.a the Emperor a.k.a Sheev Palpatine proved himself time and time again to be the most powerful villain in all of the Star Wars canon.
Aayla Secure probably had the most brutal death shown on screen in Revenge of the Sith. She and the 327th Star Corps were preparing to engage Separatist spider tanks on Felucia when Palpatine contacted Commander Bly and activated Order 66. Caught unaware, Secure never ignited her lightsaber and was shot from behind.
The scream is believed to be voiced by actor Sheb Wooley. It was featured in all of the original Star Wars films.
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.
1 Luke Skywalker
Having faced his father once before, Luke was familiar with his tactics and used the force to gain an upper-hand. In Star Wars Canon, only Luke Skywalker can be acknowledged as the one who truly defeated Darth Vader.
Within the Star Wars Legends continuity, Yoda's Jedi instructor was N'Kata Del Gormo, a Hysalrian Jedi Master, according to an in-universe legend.
Yoda will most likely win in a fight against Darth Vader because he is more skilled with a lightsaber and has the experience and feats that allow him to trim whatever size and strength advantage Darth Vader has over him. In fact, Yoda nearly defeated Palpatine, something that Vader could never do.
Darth Sidious was able to cheat his upcoming death by transferring his spirit into a clone body while falling into the reactor core of the second Death Star. He later sought to prolong his existence by futilely manipulating his grandchild Rey into killing him so he could live further by possessing her body.
Thousands of Jedi throughout the galaxy were killed, including Ki-Adi-Mundi on Mygeeto, Aayla Secura on Felucia, Plo Koon in the skies of Cato Neimoidia, Stass Allie on Saleucami, Depa Billaba on Kaller, Jaro Tapal in the Bracca system, and even Jedi younglings.
Emperor Palpatine/Darth Sidious
Portrayed by Ian McDiaarmid in the original, prequel and sequel trilogies, he is the ultimate big bad of the Star Wars universe. Palpatine restored the Sith and took full control of the galaxy, bringing many unfortunate souls along with him, such as Vader and Ren.
Having covertly turned Kylo Ren—Anakin's grandson and Luke's nephew—to the dark side, Palpatine orders Ren to find and kill Rey, the last remaining Jedi and Palpatine's paternal granddaughter. Palpatine is ultimately defeated and destroyed by Rey.
In the original Star Wars trilogy, Luke Skywalker represents the hero archetype of "the young man, called to adventure, the hero going out facing the trials and ordeals, and coming back after his victory with a boon for the community".