"Dark Lord of the Sith": A Title Explained
The designation Dark Lord of the Sith was a title borne by individuals within the Sith organization, sometimes referred to as Sith Lords. According to the tenets of the Rule of Two, it was bestowed upon both the Sith Master and their Sith apprentice.
Approximately one millennium following the death of Darth Bane, the Lord responsible for the Sith's reformation, Darth Plagueis's apprentice, Darth Sidious, plotted to bring the Sith back to prominence. During the Clone Wars conflict, Darth Maul together with Savage Opress asserted their claim to the title of Dark Lord, even as Sidious and Darth Tyranus were present. Opress was slain by Sidious, who then reprimanded Maul, reminding him, his former apprentice, that galactic time could only accommodate two Sith Lords.
Following the fall of the Galactic Republic, the galaxy found itself under the dominion of two Dark Lords: Galactic Emperor Darth Sidious and his apprentice, the Jedi who had fallen, Darth Vader. This occurred during the era of the Galactic Empire. Their rule ended when Vader sacrificed himself by eliminating his master, effectively causing the extinction of the Sith through the deaths of the last Dark Lords.
Even with the prophesied destruction of the Sith, their influence lived on by way of Sidious, who was brought back through cloning and the dark side of the Force, and also through Supreme Leader Kylo Ren, Vader's grandson. During the First Order's war against the Resistance, Ren had ambitions to govern the entire galaxy as the new Emperor and Dark Lord of the Sith. After Ren's redemption, Sidious met his end, along with his followers, during the Battle of Exegol, making him the last Dark Lord of the Sith.
Within the Sith Order, the title of Dark Lord of the Sith, also known as a Sith Lord, was utilized. The title "Darth" that was used by all Sith Lords, roughly translated to "Dark Lord."
The Valley of the Dark Lords, located on the planet Korriban, housed the crypts of the deceased Dark Lords of the Sith. This planet held a sacred status as a place for Sith ceremonial rituals. The burial ritual for a Dark Lord of the Sith was marked by hundreds of Sith warriors carrying the body of the deceased master. The body was placed in a tomb with valuable items, and slaves accompanied the deceased to the spirit realm. After the burial, the Sith would leave the planet, not returning until the next burial.
Internal conflicts over power and greed eventually plagued the Sith, which weakened the Sith Order until the Jedi Order emerged victorious, nearly destroying their age-old adversaries. However, one member of the ancient Sith Order survived: Darth Bane. Bane took on the mantle of Dark Lord and introduced the Rule of Two, decreeing that only two Sith Lords could exist at any time: a Sith Master and a Sith apprentice. Following his death, Bane became the last Dark Lord to be interred in the Valley of the Dark Lords on Moraband.
The Dark Lords who came after Darth Bane adhered to his teachings, keeping the Sith Order at two members during the millennium of the modern Galactic Republic. Darth Sidious, publicly known as Sheev Palpatine from Naboo, became the Dark Lord of the Sith by betraying and murdering his Sith Master, Darth Plagueis. Sidious held the title of Dark Lord of the Sith during the final years of the Republic and the emergence of the Galactic Empire.
During the Clone Wars, Sidious' former apprentice, Darth Maul, attempted to regain his Sith Lord status while training his brother, Savage Opress. Sidious, who had replaced Maul with Darth Tyranus, confronted the Zabrak Sith claimants on Mandalore. He killed Opress and subdued Maul. The Dark Lord then reprimanded Maul, making it clear to the Dathomirian that he was replaced in an Order that only allowed two Sith Lords. However, Sidious stated that he still had uses for his former apprentice, using him to draw out Mother Talzin.
Sidious later betrayed Tyranus, ordering Jedi Knight Anakin Skywalker to kill him, as he wanted Skywalker to become his apprentice. After Tyranus' death, Skywalker succumbed to the dark side and became Darth Vader, Sidious' third apprentice. After destroying the Jedi Order, Sidious proclaimed himself Galactic Emperor. The Dark Lords governed the galaxy for a generation until the Battle of Endor in 4 ABY, when Sidious betrayed Vader and attempted to make Luke Skywalker his new apprentice. Vader had previously attempted to do the same, but he abandoned his quest to make his son his apprentice after the mission to Exegol, and only resumed it during his alliance with the Schism Imperial.
During the Battle of Endor, Luke refused to kill his father, declaring his allegiance to the Jedi. Enraged by Luke's refusal to embrace the dark side, Sidious tortured the Jedi Knight with Force lightning. Luke pleaded with Vader to save him; unwilling to watch his son die, Vader sacrificed his life by destroying the Emperor.
The deaths of Sidious and Vader marked the end of the Dark Lords' lineage dating back to Darth Bane, and the beginning of the New Republic Era. Vader died as Anakin Skywalker, having returned to the light side through an act of selflessness and sacrifice, which allowed Yoda to preserve Anakin's identity when he became one with the Force. As a result, Anakin joined Yoda and Obi-Wan Kenobi as a Force spirit. With his death, Anakin brought balance to the Force and his destiny as the Chosen One was fulfilled.
Unknown to most of the galaxy, Sidious was resurrected when he used the dark side to transfer his spirit into a cloned body. With the help of his followers on Exegol, the Sith Eternal cult, the fallen Emperor engineered the strandcast Snoke to mold Vader's grandson, Kylo Ren, into an heir worthy of inheriting the Sith legacy. Ren, desiring the power of his Sith grandfather, aimed to rule the entire galaxy as the new Emperor and Dark Lord of the Sith.
Sidious' plan to restore his Order by establishing a new Sith Empire ended at the Battle of Exegol. Kylo Ren had returned to the light side of the Force, renouncing the dark side and his claim to the Sith mantle, while Sidious' granddaughter, the Jedi apprentice Rey, rejected the Emperor's offer to succeed him. In the end, Rey used the power of all the past deceased Jedi to destroy Sidious and the Sith once and for all.
In the non-canon story of the Star Wars: Visions short "THE TWINS," the Force-sensitive twins, Am and Karre, both possessed the title of "Dark Lord." In this role, they both wielded power over a Galactic Empire that arose after the Battle of Exegol. The twins' empire sought to seize control of the galaxy, but Karre rebelled and left the regime.