Gandalf's line "You shall not pass!" from The Lord of the Rings: The Fellowship of the Ring is something of a meme, so I naturally wondered how it was translated into German. This video has the relevant dialog (once at :40, and again at 1:15). Gandalf says "Du kannst nicht vorbei!"
There are a few issues here. First, no infinitive verb with the modal verb. It seems to be common in German to drop "gehen/kommen" from the end when you use a modal verb with an adverb or prepositional phrase indicating direction. So the verb is not actually required here.
Second, the German uses können instead of the future tense as in the English version. To me this changes the meaning somewhat, and the "shall" is significant in light of what happens next. But perhaps this is a matter of interpretation.
What I'm stuck on is why Gandalf uses the 'du' form in this speech. The grammars say that the 'du' form is used for friends and family members, sometimes children and pets. So I would have thought "Sie können nicht vorbei!"
My first idea is that since the Balrog does not speak, it's taken to be some kind of animal. To me, this doesn't fit the story; the Balrog is a kind of demon and is intelligent despite being unwilling or unable to speak in the scene. Plus you don't see many animals wielding whips. My second idea is that Gandalf is being deliberately unhöflich by using 'du'. Perhaps this is to distract the Balrog, bait it into trying to cross the bridge, or just to show his contempt. Are either of these likely or is there another explanation?