The Sith were a red-skinned species with tentacles, susceptible to using the dark side of the Force. They shared their name with the Sith, a religious order of Force-sensitives who used the dark side.
Behind the scenes
The Sith were canonically mentioned in Star Wars Workbook: 3rd Grade Reading and Writing, published in 2017 by Workman Publishing. In the Star Wars Legends continuity, the species made their first appearance in the fifth issue of the Star Wars: Tales of the Jedi comic miniseries, written by Tom Veitch and published by Dark Horse Comics in 1994.
- Star Wars Workbook: 3rd Grade Reading and Writing (First mentioned)