Louisa Ulrika of Prussia

Louisa Ulrika of Prussia was Queen of Sweden between 1751 and 1771 by her marriage to King Adolf Frederick, and queen mother during the reign of King Gustav III.

Louisa Ulrika was born in Berlin as the daughter of Frederick William I of Prussia and his wife Sophia Dorothea of Hanover, and was thus a younger sister of both Wilhelmine of Bayreuth and Frederick the Great. She was given the Swedish name Ulrika because Queen Ulrika Eleonora of Sweden had been her god mother. She exchanged letters with her godmother, and it was thought that she would marry a future son by Ulrika Eleonora, as Ulrika Eleonora herself had once been considered as a consort for Louisa Ulrikas father. However, Ulrika Eleonora remained childless.

Source: Wikipedia