Kylo isn't a Sith. He's "just" a Dark Jedi and a member of the Knights of Ren. We don't know whether the Knight of Ren are all dark side users and we don't know who or what is Snoke.
History. A dark side warrior with a mysterious past, Kylo Ren was neither Jedi nor Sith, but a product of both sides' teachings. Once an apprentice of Luke Skywalker's, he killed his fellow students and drove Skywalker into exile, becoming a First Order warlord and servant of Supreme Leader Snoke.
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).
Kylo Ren was not a Sith. The Sith had died out after the “death” of Palpatine. He changed is name to distance himself from his family, especially his father. His last confrontation with Han is what caused Ren to become Ben once more.
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 ...
“So Leia Force projects herself as Ben and uses her life force to save Rey. Even going as far as to kiss Rey to convince her it's Ben. It's why when Ben disappeared, so did Leia.”
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 Rey, born Rey Palpatine, was a Force-sensitive human female who served the Sith Eternal during the New Republic Era.
She is the grand-daughter of Darth Sidious as well as the protégé of Luke Skywalker. She has a unique connection to both sides of the Force. This begs the question – which side of the Force resonates the best with Rey? Technically speaking, she is a Jedi.
Snoke Is Not a Sith Lord
He was never given one because he isn't technically a Sith Lord. But the fact that he's a bio-engineered being created by Palpatine explains why his training of Kylo Ren followed the Sith mold so closely, since all along Palpatine was trying to manipulate Ren.
The strongest among the Exiles, Ajunta Pall, became the first to hold the title Dark Lord of the Sith. His contemporaries, such as Karness Muur and XoXaan, became Sith Lords. The human Dark Jedi interbred with the Sith species, who also had an affinity for the Dark Side. They would become the original Sith Empire.
Organization. Darth was a title given to certain Sith Lords which preceded either their chosen Sith name, or, in some cases, their birth name.
Though initially trained as a Jedi by his uncle Luke Skywalker, Ben was seduced to the dark side of the Force by Supreme Leader Snoke, and aspires to be as powerful as his grandfather, the Sith Lord Darth Vader / Anakin 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.
Darth Sidious and Darth Vader were the last Sith Lords who followed Bane's Rule of Two. The war's end in 19 BBY, a thousand years after Bane's death, saw the culmination of the Sith's millennium-long vendetta against the Jedi. Sidious declared himself Emperor and reformed the Republic into the Galactic Empire.
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.
A crystal embodies the Jedi as the heart of the lightsaber, and pure kyber has no color until it's bonded to the Force user. This process likely resulted in Rey Skywalker's lightsaber being yellow.
Rey's lightsaber was a yellow-bladed lightsaber that was constructed by the Jedi Rey Skywalker following the First Order-Resistance War.
Whereas Obi-Wan buried both Anakin's and his own lightsaber, Rey buried Luke's and Leia's while creating a new one for herself. She lived in a different era, when Jedi light was re-emerging and she had nothing to fear. Her decision to bury Luke and Leia's lightsabers was an attempt to give them a new legacy.
Darth Nihilus
Nihilus is a truly terrifying presence throughout the game and was truly beyond evil.
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.