Answer
Ulrika Eleonora's husband, Frederick I of Sweden, was the Landgrave of Hesse-Kassel before ascending to the Swedish throne. He was born into the noble House of Hesse and ruled as Landgrave of Hesse-Kassel from 1720 to 1730. Frederick's marriage to Ulrika Eleonora, who was the reigning Queen of Sweden, brought about the union of the Swedish and Hessian royal families.