Justine Cathrine Rosenkrantz (1659 – 1746) was a Danish lady-in-waiting, noble and spy.
Rosenkrantz was the daughter of baron Ludvig Rosenkrantz. Between 1680 and 1699, she was the lady-in-waiting to the queen of Denmark, Charlotte Amalie of Hesse-Kassel. She was placed in her position to act as a spy on the queen by the queen's enemies; officially to place a Lutheran in the court of the queen, who was otherwise dominated by people of the reformed faith. Rosenkrantz was described as unattractive but very skillful in the art of handling the plots of the royal court and an excellent informer and held a powerful position at court—it was also noted that she was rude and a torment to the queen. She fell form her position after a great scandal in 1699, when she poisoned the soup of her colleague Anna Emilie von Dalwig, who was her rival over her love interest Friedrich Emanuel von Køtschau: Dalwig survived the poisoning, but Rosenkrantz was sentenced to death for attempted murder 17 April 1699, which was commuted to exile in Rønne.