(But in the science fiction novel Dune, Kwisatz Haderach is a title, not a name, and basically means "Messiah" or "Anointed Chosen One" -- i.e, there is only one, and so it takes "the" in English.)
Thank you. Well, I've read it many years ago in Russian. Thus I forgot some important things about this amazing novel.
Anyway, it concerns not only names, of course. Я - мессия! Я - избранный!