Darth Nihilus is the primary antagonist featured in Star Wars: Knights of the Old Republic II: The Sith Lords. Once considered human, his thirst for power drove him to the depths of the Dark Side of the Force. He, along with Darth Sion and Darth Traya, formed the Sith Triumverate.
To get the mask, I printed the pattern onto paper by Inkjet, and then wrapped it around the head and held it in place with the hood. No glue needed!