Justine Cathrine Rosenkrantz (1659 – 1 August 1746) was a Dano–Norwegian noblewoman, courtier and spy.
Between 1680 and 1699, she was lady-in-waiting to Christian V's queen consort, Charlotte Amalie of Hesse-Kassel.
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 from 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 Emanuel Friedrich von Kötzschau [de].
Dalwig survived the poisoning, but Rosenkrantz was sentenced to death for attempted murder on 17 April 1699, which was commuted to exile in Rønne.