Billy
... that unlike many slasher film antagonists, the true identity and motivations of the character Billy in Black Christmas are never revealed?
... that unlike many <a href="./Slasher_film" id="mwB5k" rel="mw:WikiLink" title="Slasher film">slasher film</a> antagonists, the true identity and motivations of the character <b id="mwB5o"><a href="./Billy_(Black_Christmas)" id="mwB5s" rel="mw:WikiLink" title="Billy (Black Christmas)">Billy</a></b> in <i id="mwB5w"><a href="./Black_Christmas_(1974_film)" id="mwB50" rel="mw:WikiLink" title="Black Christmas (1974 film)">Black Christmas</a></i> are never revealed?