A Sith warrior represented a specific type of warrior in service to the Sith Order, irrespective of whether the organization was the main Sith body or a derivative faction. Throughout the extensive galactic history, various Sith warriors existed, including the Dowutin Sith sect from ancient times, the individual known as "the Stranger" during the High Republic Era, and the two Dathomirian brothers, Maul and Savage Opress, in the latter part of the Republic Era.
Warriors who were in the service of the Sith were considered Sith warriors. Each Sith warrior, adhering to the Sith Code, embraced the principles of unparalleled strength, dominance, and triumph, and was expected to be prepared to undertake any action to accomplish their objectives as Dark Lords of the Sith. The designation was utilized both in the ancient days of the Sith Order, during the period of the Order's Rule of Two, and within a separate Sith Order established by the former Sith Lord Maul and his sibling Savage Opress, both of whom operated as Sith warriors and styled themselves as Sith, despite not holding a formal claim to the title of Dark Lord at that juncture.
During the period when the Sith Order existed, a sect consisting of Dowutin Sith warriors forged the Sword of Khashyun. "The Stranger" functioned as a Sith warrior. Darth Maul, who was the Sith apprentice of Darth Sidious, was known as a Sith warrior. Following Maul's presumed death during the Battle of Naboo, Sidious chose to take on a new apprentice, the former Jedi Master Dooku; however, Maul had in fact survived and maintained his status as a warrior. His brother, Savage Opress, underwent training as a secret apprentice under Dooku and was regarded as a Sith warrior. Eventually, however, Oppress broke free from Dooku's control and was reunited with his lost brother, who initiated a new revenge scheme with Oppress at his side. Despite no longer being part of the official Sith Order, given that the Rule of Two stipulated that only a master and an apprentice—Sidious and Maul's replacement, Dooku—could exist simultaneously, Maul proclaimed himself the master of Oppress within their own adaptation of the Rule of Two.
As Sith warriors within Maul's unofficial Sith Order, the pair established the criminal Shadow Collective, which seized control of the planet Mandalore. However, Sidious himself appeared to confront his former disciple, whom he derided as no longer being a member of the Sith. Sidious also succeeded in killing Oppress, while Maul was defeated and imprisoned within Spire by Dooku's Confederacy of Independent Systems. Although Maul was later freed by his Mandalorian super commandos, he was used by the Sith as bait to draw out the Nightsister Mother Talzin, his benefactor and biological mother. During the Second Battle of Dathomir, Talzin was killed by the Sith and their agent Grievous, and Maul subsequently lost his power base during the Siege of Mandalore. At some later point, Maul relinquished his title of "Darth" and disavowed any remaining connection to the Sith religion.
When Jedi Grand Master Yoda journeyed to the Sith homeworld of Moraband as part of his quest to uncover the secrets of immortality during the Clone Wars, apparitions of figures identified as ancient Sith warriors manifested before Yoda, taunting him by asserting that there was no way to survive beyond death. These warriors were illusions created by the power of the dark side itself, as well as the Force Priestesses, beings who guided and tested Yoda throughout his journey. Ultimately, Yoda successfully completed all the trials presented to him and, as promised by the Priestesses, was thus able to train with the Force spirit of Qui-Gon Jinn to learn how to maintain his identity after death.
Star Wars: Rebel Heroes refers to Maul as a Sith warrior during the events depicted in "Twilight of the Apprentice." However, in that particular episode, Maul explicitly states that he has abandoned his ties to the Sith.