On a tiny bridge with a wooden staff and a terrible case of split-ends, Gandalf the Grey stood his grown against the giant fire demon Balrog.  Gandalf had to protect Frodo, the One Ring, and all his companions so we could make it to the sequels.  Until now, Gandalf was just an old guy with a bad ass sword and some surprisingly kick ass moves, but for a powerful wizard, he wasn’t much.  Until now.  With an energy shield protecting himself from Balrog’s whip, Gandalf prevented the demon from pursuing the Fellowship, echoing the magic words "You shall not pass."  The constant repeat and emotional climax led the demon’s fall, and ironically Gandalf’s as well, for now.  So sad.  The book original had Gandalf saying "You cannot pass."