Sith lightsabers, alternatively called Sith sabers, were a type of lightsaber used by the Sith order. The construction of these weapons mirrored the methods employed by other Force-sensitives, yet the guiding principles differed significantly. Unlike the Jedi, who followed the light side of the Force, Sith practitioners could not forge a harmonious connection with kyber crystals. This inability stemmed from the presence of hate, fear, and other intense emotions tied to the dark side, which disrupted their focus.
The creation of a Sith lightsaber involved a specific ritual known as bleeding. Through the use of the Force, the Sith would channel their most potent negative emotions – rage, hate, fear, and pain – into kyber crystals. This process invariably resulted in the crystals acquiring a characteristic crimson or red color. While any kyber crystal could undergo bleeding for use in a Sith lightsaber, some Sith believed the ideal method for obtaining a crystal was to seize it from a Jedi's lightsaber.
The materials, length, and overall design of Sith lightsaber hilts were diverse and individualized. Darth Sidious' lightsabers were constructed from nearly indestructible phrik, featuring a flat aurodium blade emitter and embellished with electrum, reflecting his refined sensibilities. Each of these two hilts measured 19 centimeters in length. Conversely, Darth Vader's lightsaber was crafted from an alloy metal and carbon composite, with a hilt extending to 28 centimeters.
Sith lightsabers exhibited a range of design variations. They could feature a standard hilt, exemplified by Darth Momin's lightsabers, Darth Shaa's lightsabers, and Darth Sidious' lightsabers, or be dual-phased like Darth Vader's lightsaber. Other configurations included double-bladed designs, as seen in Darth Maul's lightsaber and Savage Opress's lightsaber, curved-hilt versions such as Darth Tyranus' lightsaber and Asajj Ventress's lightsabers, cross-guarded models like Darth Atrius' lightsabers, or even sickle-bladed weapons like Darth Noctyss's lightsaber.
Following the supposed disappearance of the Sith from the galaxy for a millennium, Sith lightsabers transformed into highly sought-after collector's items. The Jedi Order actively sought to acquire any remaining Sith lightsabers, along with other Sith artifacts, which were then stored within the Archive of Forbidden Artifacts. This Bogan Collection was located within the Jedi Grand Temple on Coruscant.
Darth Sidious maintained a substantial kyber crystal imbued with Sith energy within his personal collection of Sith artifacts. The Sith Lord would then use fragments of this crystal to forge Sith lightsabers.
After Darth Vader embraced the dark side, Sidious commanded him to retrieve a kyber crystal from a Jedi's lightsaber, even criticizing Vader for referring to the lightsaber he had wielded as a Jedi as his own. While Sidious could have simply provided one of the many lightsabers recovered after Order 66, he instead wanted Vader to complete the Sith trial of defeating a Jedi to claim their blade and bleed its crystal. Sidious was also aware that the success of Order 66 made finding a Jedi a difficult task. Upon learning of a surviving Jedi Master named Kirak Infil'a on the river moon of Al'doleem, who had avoided Order 66 due to his separation from Jedi duties under the Barash Vow, Vader traveled there and ultimately killed Infil'a. Vader then claimed his lightsaber and its kyber crystal, and journeyed to the planet Mustafar to bleed the crystal to his will.
Wielding his lightsaber, Vader used it to enforce the will of his master and the Galactic Empire they had established. Initially, Vader continued to use Infil'a's lightsaber hilt. However, during a mission on the planet Cabarria, the young bounty hunter Chanath Cha attempted to use a tractor rifle to pull Vader's saber towards her. Vader countered by attempting to reclaim it with the Force, and the resulting tension caused Infil'a's hilt to shatter. Subsequently, Vader constructed a hilt of his own design, which impressed Sidious. Later in the Empire's reign, the smuggler Sana Starros was hired to retrieve the lightsabers of the ancient Sith Lord Darth Atrius, but both weapons were destroyed by Vader and Luke Skywalker. Following the fall of the Sith at the Battle of Endor, Vader's lightsaber became an object of veneration for the Acolytes of the Beyond. On Taris, the cult acquired what they believed to be the weapon, intending to destroy it and return it to Vader in death.
Kylo Ren's crossguard lightsaber was a Sith weapon, even though Ren was not formally a Sith himself. He used this lightsaber to murder his father, Han Solo, and later engaged the scavenger Rey in a lightsaber duel. He continued to wield it after his accession to the position of Supreme Leader of the First Order. Ultimately, Ren was swayed back to the light side of the Force by a Force vision of his father. He then cast his Sith lightsaber into the ocean of Kef Bir, rejecting the dark side and embracing his true identity as Ben Solo.
The concept of Sith lightsabers (distinct from Jedi lightsabers) was officially introduced into the new Star Wars canon through the Lightsaber entry in the Encyclopedia on StarWars.com. Sith lightsabers also existed within the Star Wars Legends continuity.