Darth Vitiate had also achieved functional immortality and shared it with Darth Scourge after the latter captured Revan for him. If you mean Sith Force Ghosts, lots of Sith have achieved that: Marka Ragnos, Freedon Nadd, Naga Sadow, Ajunta Pall, Exar Kun, Zash, and Sidious just to name a few.
Out of the many Dark Lords of the Sith, Plagueis was one who was said to be able to achieve the power to stop death. Although he could not achieve immortality for himself, he managed to manipulate the Force in such a way that he was able to create life.
Ultimately, the Emperor's vision of a galaxy eternally ruled by the Sith ended when his clone body was destroyed by his own power. Sidious was vanquished in both body and soul, and his dream of immortality died with him.
Now, Darth Vitiate lived for around 1,500 years, which is by far the longest lifespan of any Sith Lord on this list. With a major appearance in Star Wars: The Old Republic, Darth Vitiate presented himself as one of the big bads in the Star Wars universe.
Darth Andeddu, also referred to as the Immortal God-King of Prakith, was an ancient humanoid male who reigned as Dark Lord of the Sith, and was dubiously thought of as the forebear of the "Darth" title.
Emperor Vitiate was a Sith Lord who successfully gained near immortality by draining the life force of an entire planet, later attempting to drain all life in the galaxy, which would give him true immortality.
Darth Shain, headmaster of the Korriban Temple, took notice and convened with the Dark Councilor and Dark Lord of the Sith Darth Shane McMahon, who decided to confer the title of Sith Lord to the young apprentice at the age of 11, making him the youngest Sith Lord in the history of the Sith.
Eventually, Sion was struck down, but he did not die. Instead, the pain within him welled up to agonizing levels, driving Sion to rise once more and strike down his would-be killer with all his anger and hate. Sion found that he could hold his own decomposing body together with the dark side of the Force.
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.
Why Qui-Gon Jinn Was Palpatine's Greatest Threat. Unlike Yoda and the Jedi High Council, Qui-Gon Jinn was only concerned about the will of the Force. Therefore, Palpatine needed Qui-Gonn out of the way because he was better connected to the Force than the other Jedi.
In Revenge of the Sith, we see Darth Sidious seemingly deformed by his own deflected Force lighting. Right off the bat, this is by far the most popular and likely explanation for his appearance.
With the betrayal and near destruction of the Jedi Order, Sidious dissolved the Galactic Republic and replaced it with the Galactic Empire. Ruling as emperor in his public guise as "Palpatine", Sidious' reign was prophetically ended by his own apprentice—the Chosen One, Anakin Skywalker.
He became so powerful… the only thing he was afraid of was losing his power, which eventually, of course, he did. Unfortunately, he taught his apprentice everything he knew, then his apprentice killed him in his sleep. Ironic.
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.
He found the key to immortality.
By using the living and cosmic Force in tandem, he was able to unlock the secrets of eternal life.
By 44 ABY, the true Sith species in the Empire were believed to have gone extinct due to the interbreeding process. Characteristics shown would be determined depending on how much Dark Jedi or Sith blood an individual possessed due to interbreeding.
A Sith Lord with the ability to cheat 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.
The deaths of Sidious and Vader marked the end of the lineage of Dark Lords going back to Darth Bane, and the beginning of the New Republic Era.
Even though Kylo Ren uses a red lightsaber, harnesses the dark side of the Force, and wears a cape, he is not a Sith. Because of that, he can never hold the title of Darth. Instead, he was just a chaotic mess of the dark side (until he eventually found his way back to the light).
By far one of the cruelest Sith to ever live, Vitiate was created as an antagonist for the game Star Wars: The Old Republic, in which he was responsible for killing his parents at age ten, and later kickstarting the Mandalore Wars, the Jedi Civil War, and in his quest to remain Emperor of the Sith for all time, the ...
Without question, the most powerful Force ability present in Star Wars is the Thought Bomb. It is created through an ancient Sith ritual where the Sith combine their dark side powers. If done successfully, the Thought Bomb can destroy all Force-sensitive beings unfortunate enough to be within the radius of its blast.
All of the following had the reputation as being acedemics or intellectuals darth plagueis the wise, Darth Sidious, Obviously Darth Traya, Revan, Marka Ragnos, Naga Sadow and vitiate. As far as the smartest Sith Ever I say Darth Plagueis or Darth Traya followed by Sidious and Darth Vitiate.
The earliest Sith lived on the red, dusty planet of Korriban, determined to grow strong despite the inhospitable climate. Their success culminated in a bold civilization, made stronger when dark Force-users arrived and interbred after being driven out of the early Jedi Order.
The average lifespan for a Sith, without any assistance from medical technology, is around 250 years. Taking into account that Force sensitive beings have extended lifespans, most Sith can reach up to 400 years.