Star Wars' central theme of the light against the dark has primarily manifested itself through the Jedi and Sith. But while there have been many Jedi in movies, the Sith ranks are filled with Star Wars Legends characters who have not appeared on the big screen, such as Darth Revan and Exar Kun. Most of these Sith lived hundreds to thousands of years before the birth of Anakin Skywalker. Several Sith Lords also have unique stories of their own that make them worthy of standalone movies.
Source：https://www.cbr.com/star-wars-legends-sith-lords-deserve-movie/
