Ellen Marsvin (1 February 1572 – 11 November 1649) was a Danish noble, landowner and county administrator.

She was the mother-in-law of King Christian IV of Denmark-Norway, the mother of Kirsten Munk (1598–1658) and grandmother of Leonora Christina Ulfeldt (1621–1698).

[1][2][3][4] She was born at Landskrona Citadel in Scania (Skåne), a part of Denmark that was conquered by Sweden in 1658 and has been Swedish since.

Ellen had demanded that her daughter be married rather than be mistress to the king; she also formed the marriage contract, in which it was stated that Kirsten should be the legal spouse of the king and receive a county as widow pension.

Through her inheritance, money and connections, she bought, sold and built large estates with great success.