A Nightsister Force crystal was a crystal native to Dathomir that was capable of enhancing the Nightsisters' Force abilities. Nightsisters wore it as part of their elaborate headdresses. Imperial Inquisitor Xarot Korlin, who had been studying the indigenous Nightsisters' ways of using the Force, sent an agent to kill one of them to obtain one of these crystals for his studies. It is likely that the Nightsister Charal used one during her time on Endor.