These are either Danish or
German names. Gyldenstjerne (Guildenstern) means "golden star". Rosenkrantz (Rosencrantz) means "rose wreath". There are several different spellings of both of these names. This is just some information I found:
Rosenkrantz:
Meaning rose wreath. It is an ashkenazic-ornamental surname (ashkenazic means a Jew of Eastern European or
German descent) from the word for flower or metronymic from the Yiddish female given name Royze derived from the word for flower.
http://www.shaksper.net/archives/2001/1434.htmlThis webpage has a lot more useful information if you want to check it out, but here's part of it:
Rosecrantz and Guildenstern could, indeed, seem to be Jewish names, but they are not. Nor are they 'normal' Danish names. They are anglified versions of the names of the very eminent Danish noble families of 'Rosencrantz' and 'Gyldenstjerne'. The senior members of these families held almost permanent places at the Danish council of the realm (equivalent of the privy council in England) throughout the middle ages and for some time after. It is entirely plausible, therefore, that junior members should have been ambassadors to various courts of Europe. Incidentally, one member of a cadet branch of the Gyldenstjerne family, Sir
Andrew Ogard (after the family estate Aagaard in Jutland) emigrated to England, participated in the Hundred Years' War, was knighted by, I think,
Henry V, and became the forefather of Rider Haggard.
Rosenkrantz Danish Origins:
There were no family names at the time of
Erik the Knight. The name Nielsen simply meant that
Erik's father was named
Niels; Nielsen translates to
Niels' son. In 1525,
Frederick I commanded all of the Danish noble families to adopt family names. The descendants of
Erik and his brothers adopted the name Rosenkrantz, which means "wreath of roses" in Danish and related Germanic languages. Thus the Rosenkrantz name and its variants are in use today by the descendants of
Niels Iversen,
Erik's father.