Indefinite article before proper names

[sergeyrais]

Is there any special grammar rule to explain the article in the phrase the Dark Knight?
Are variants a Dark Knight, or Dark Knight (without an article) possible?

 

[5jj]

'The Dark Knight' is not a particular phrase. When we are talking about one or more dark knights, then we use articles, or not, as appropriate. In a film title, we can choose what sounds best.

 

[emsr2d2]

If you're using a proper noun to show that something is an example of something, then yes.

My boss has a Picasso hanging in his study = My boss owns a painting by Picasso and the painting is hanging in his study.
I went to a Rolling Stones' gig last night
I'd like to buy a Renault Clio please.