Nightsisters

The Nightsisters were a group of Dathomir Witches and sith lords, led by Sai Sircu. They Tried to steal lightsaber crystals for their ship, the devastation. However, once Anakin and Mace Windu defeated Sai Sircu, the nightsisters disbanded.

Trivia
The nightsister on the sedawan talks perfectly. However, Sai Sircu talks in a slurred speech.

General Grievous is the only member of the confederacy who has not met the Nightsisters.