During the Clone Wars, there was a coven under the leadership of Mother Talzin, who welcomed back and helped Asajj Ventress in her quest for vengeance against Dooku, who had betrayed her. Which is where the Night Sisters Trilogy came into play.
Anyway, after seeing the episode last night, I was on the Star Wars blog and found this wonderful image of a Sith Witch cosplay and I decided to share. You also should check out the link to Bryan Humphrey's Deviantart gallery because he is just awesome! I see a lot of Cosplay of the Day coming from there if he let's me, lol. Anyway, Sith Witch portrayed by Mary Ellen Berglund.
Night Sisters info provided by:
First discovered Sith Witch at: