A Sith torture mask was a hood used by the Sith when interrogating prisoners, especially Jedi Knights. The prisoner would be forced to wear the mask, which was both unremarkable to behold and covered the entire head except the eyes. This allowed the captured being to see what was happening to them. While resembling ordinary masks, the torture mask was actually imbued with dark side energy preventing Jedi from calling upon the Force by stopping them from concentrating.
Asajj Ventress kept a Sith torture mask in Castle Ventress on Rattatak, where she used it on Obi-Wan Kenobi following the Battle of Jabiim.
- The Complete Star Wars Encyclopedia