Eleonora was born at Stegeborg Castle in Östergötland, Sweden to Princess Catharina of Sweden and Johann Casimir, Count Palatine von Zweibrücken-Kleeburg. Her mother was an elder half-sister of King Gustavus Adolphus of Sweden and the firstborn daughter of King Charles IX. Her parents, who were second cousins, had lived in Sweden since 1622, and Eleonora and her siblings, including her sister Maria Eufrosyne, grew up in Sweden as foster siblings of their cousin, Queen Christina of Sweden. Eleonora was only about seven months older than Christina and had the same teacher, Johannes Matthiæ. The negotiations concerning her marriage with Landgrave Frederick of Hesse-Eschwege, son of Maurice, Landgrave of Hesse-Kassel, started in 1643. The landgrave was a second cousin of both her parents and nine years her senior. The negotiation process was difficult, but finally completed in June 1646. She was granted a fortune of 20,000 gulden by her father. The marriage took place at Tre Kronor in Stockholm on 6 September 1646. After the wedding, Eleonora confessed before her husband, "on her knees", that she had had an affair with a French lute-player and actor, named Beschon, from the French court theatre of Antoine de Beaulieu, and was pregnant with his child. Frederick decided to act like nothing happened and hide the matter, but it became a known scandal. Beschon wrote a composition to Eleonora which he sent her along with a letter dated 28 February 1647, but she gave it to her brother; this document is now preserved in the Stegeborg collection. In 1648, she referred to the queen's head lady-in-waiting Margareta Brahe as her "Dearest Protection", likely because Margareta Brahe had defended her when she gave birth to an illegitimate child. The marriage has been described as unhappy. Frederick took part in the war of his brother-in-law in Poland, where he was shot in 1655. Eleonora never remarried. It is said she was too embarrassed by the scandal with Beschon to return to the Swedish court, so she preferred to live in her fief Osterholz, where she founded a pharmacy and hired the first teacher and doctor of the town. Eleonora was the administrator and regent of her husband's possessions in the Holy Roman Empire. Eleonora sent her daughter Juliana to be brought up at the Swedish royal court, where she was regarded as a prospective bride for Charles XI until she became pregnant in 1672. Eleonora did in fact visit Sweden a couple of times: in 1661, in 1674 and in 1681. During her 1674 visit, Lorenzo Magalotti described her as "a wicked, vain, strange, proud and melancholic woman" who spent most of her time in pious devotions. Eleonora died in Osterholz, Bremen and is buried at the Altstädter Kirche in Eschwege where now stands the Marktkirche. Some of her notable descendants are Wilhelm II, German Emperor; Nicholas II of Russia; Queen Victoria of the United Kingdom; Charles, Prince of Wales; and the present king of Sweden, Carl XVI Gustaf.
