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.
According to Star Wars Legends content, the first Sith was a former Jedi Master, Ajunta Pall, who became a so-called Dark Jedi, or “Fallen” Jedi. As the name implies, these Force-sensitives chose to practice the Dark Side, and rejected the Light Side of the Force.
Although it's not fully clear where the Darth moniker originated, Darth Andeddu is thought to be the first character to use the title in-universe. Having originated in Legends, Andeddu was mentioned in the new canon in the comic Star Wars Adventures: Return to Vader's Castle 2, which referenced "Andeddu's flames".
While many Sith Lords are mentioned, only six are detailed in canon: Bane, Plagueis, Sidious, Maul, Tyranus, and Vader. In addition to these Sith Lords, there are a number of other fallen Jedi, apprentices, and dark Force users.
Immortality, or eternal life, was a state in which a living being could live without ever dying. Darth Plagueis, a Sith Lord in the years prior to the Clone Wars, lusted for immortality. According to his apprentice, Darth Sidious, Plagueis manipulated the midi-chlorians to both create life and seek immortality.
Historical information
The One Sith, also known as the New Sith Order, was a sect of dark side warriors and devotees founded by the self proclaimed Darth Krayt that followed a revised doctrine of the Sith ways.
All too often, squabbling Sith in their bid for power upended carefully laid plans. After the Sith were decimated by the Jedi Knights of a thousand years ago, Bane enacted the Sith rule of two: there would be only two active Sith at one time -- a Dark Lord to embody the power, and an apprentice to crave it.
Emperor Palpatine / Darth Sidious.
Darth Sidious
Sidious is extremely powerful and held very complex knowledge of techniques to master the dark side's force energy.
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.
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.
Yoda. Yoda was a wise, experienced, and powerful Grand Master of the Jedi of an unknown species and the oldest known prophet in existence (having lived at least 900 years), considered the wisest and most powerful Jedi Master within the Star Wars universe.
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.
N'Kata Del Gormo was a Force-sensitive male Hysalrian Jedi Master who lived during the times of the Galactic Republic. According to legend, he found and trained Yoda and a Force-sensitive Human friend.
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.
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.
Darth Rey, born Rey Palpatine, was a Force-sensitive human female who served the Sith Eternal during the New Republic Era. She fought on the side of the First Order in the war against the Resistance.
Most likely not commonly known by many casual Star Wars is that, at least in Legends, the Sith had their own “chosen one” prophecy and that the central figure in it was believed to have been the Sith Lord, Darth Bane.
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.
It has to be Obi-Wan, followed by Ahsoka. He met all the Sith Lords we've seen in canon. He dueled and defeated Darth Maul, and then later killed Maul after the latter was no longer a Sith.
He then orders Ren to bring Rey (Daisy Ridley) to him after she refuses to disclose the map to Luke. After Ren is defeated in a lightsaber duel with Rey, Snoke orders Hux to bring Ren to him to complete his training.
Palpatine tells Anakin of the legend of Darth Plagueis, a Sith Lord who was said to be so powerful he could both create life and prevent people from dying.
Galen was secretly trained as a Sith Lord apprentice to Vader, but returned to the light side and the Jedi. Galen Marek is the only one who came close to destroying the Sith Lord, thanks to his vast knowledge of Vader's fighting tactics through the many hours they trained together.
Jedi Master Yoda is the most powerful of them all. This should come as no surprise, as he was the head of the Jedi Order in the prequels and was revered for his abilities during the original trilogy. Yoda's power is unmatched and was a real threat to Darth Vader and the Imperials.