The Sith were a species characterized by red skin and the presence of tentacles, and they were inclined to embrace the dark side of the Force. Their designation was also used by the Sith Order, a religious group of individuals sensitive to the Force who similarly practiced the dark side.
In the time leading up to the Galactic Civil War by centuries, one member of the Sith species belonged to the Darkseekers, a specialized division within the Sith Order. During the attack on the Ascendant temple, this Sith, wielding a lightsaber, fatally wounded the Ascendant member Ilith, resulting in his death.
The Sith, as a distinct species, received a canonical mention in Star Wars Workbook: 3rd Grade Reading and Writing, a publication from 2017 by Workman Publishing. The species made its initial appearance in a flashback within the twenty-ninth issue of the comic series Star Wars: Doctor Aphra (2020), created by Alyssa Wong.
Within the Star Wars Legends continuity, the Sith species was initially referenced in the first issue of The Freedon Nadd Uprising story arc from the Star Wars: Tales of the Jedi comic book series, penned by Tom Veitch, with illustrations by Tony Akins, and brought to publication by Dark Horse Comics on August 2, 1994. Their first visual representation occurred in the first issue of the Dark Lords of the Sith story arc in the Star Wars: Tales of the Jedi comic book series, authored by Tom Veitch and Kevin J. Anderson, with pencils by Chris Gossett, and released on October 4, 1994. This issue showcased Naga Sadow, whom later sources identified as a Human/Sith hybrid possessing a human-like appearance, while Vodo-Siosk Baas characterized him as "a member of an elite priesthood, of pure Sith blood."
The species makes an appearance in a flashback scene, mirroring the completely-red flashback from Doctor Aphra (2020) 29, which obscures the skin's true color, in the comic Tales of the Jedi – The Golden Age of the Sith 0, written by Kevin J. Anderson, with pencils by Dario Carrasco, Jr., and published by Dark Horse Comics on July 1, 1996. The modern depiction of the red-skinned Sith species was first seen in the second issue of The Golden Age of the Sith story arc within the Star Wars: Tales of the Jedi comic book series, created by Kevin J. Anderson and with pencils by Dario Carrasco, Jr., and released on November 13, 1996.
The species' history was later retconned by the 2012 reference material Book of Sith: Secrets from the Dark Side, which depicted Sith King Adas as having initially appeared in a flashback sequence within the fifth issue of the Star Wars: Tales of the Jedi comic miniseries, authored by Tom Veitch and released by Dark Horse Comics on February 15, 1994.