Peter III of Russia
Empress Elizabeth arranged for Peter to marry his second cousin, Sophia Augusta Frederica (later Catherine the Great), daughter of Christian August, Prince of Anhalt-Zerbst and Johanna Elisabeth of Holstein-Gottorp. The young princess formally converted to Russian Orthodoxy and took the name Ekaterina Alexeievna (i.e., Catherine). They married on 21 August 1745. The marriage was not a happy one but produced one son, the future Emperor Paul, and one daughter, Anna Petrovna (20 December 1757 – 19 March 1759). Catherine later claimed that Paul was not fathered by Peter: that, in fact, they had never consummated the marriage. During the sixteen years of their residence in Oranienbaum, Catherine took numerous lovers, while her husband did the same in the beginning.
Catherine of Guelders
Catherine of Guelders was the fourth and youngest child of Arnold, Duke of Guelders (1410-1473) and Catherine of Cleves (1417–1479).
Until 1477, she led an inconspicuous life, in the shadow of her brother Adolf, at war with his father, and her sisters Mary, married to King James II of Scotland and Margaret, married to Frederick I, Count Palatine of Simmern. Despite efforts by her father, no suitable husband was found for Catherine. 17th century theories that she was secretly married with Louis de Bourbon, Bishop of Liège, are now believed to be false.