The process of making a film is oft an ever-changing journey. One such changed aspect was the helm worn by the Witch-king during The Return of the King. Whilst this first design was manufactured, and even had scenes shot, it was ultimately decided that its likeness to Sauron's own helm might be perplexing for the audience. Therefore, it was replaced with the Morgul Lord War Mask seen in the final cut of the film.
Greatest of the Nazgûl was their leader, the Witch-king of Angmar. Once a mortal man lured by the promise of power, the former King of Men fell under the sway of Sauron until he was little more than an extension of the Dark Lord’s presence, his own identity long forgotten.
A formless wraith, fear was his greatest weapon, and it was said that by the hand of no man would he fall. For centuries he served his dark master, leading the campaign that saw Arnor destroyed in the north and bringing war to Gondor in the south. Even being sealed in a magically warded tomb could not contain the Witch-king, who was recalled from beyond the grave to serve his master again.