Actually,
Chevalier does mean "Knight". "Horseman" is
Cavalier, that's not exactly the same but people make the mistake.
So there is an exact translation of "Knight" in French. I don't know about the German.
And the exact translation of "The Dark Knight" in French is
Le Chevalier Noir or
Le Chevalier Sombre (but this one is a word-for-word translation, so it isn't very good). So, this is not
Le Chevalier Foncé like I read it

. This is, believe me, a very faithful translation. But I hope that won't be the French title. ^^
Sorry if my English isn't very good, I'm just a 17 years old frenchman.^^