Gustavus Samuel Leopold was born at Stegeborg Castle near Söderköping in 1670 as the youngest son of Adolph John I, Count Palatine of Kleeburg. The siblings were reportedly badly treated by their parents, and in 1687, Gustav helped his sisters Catherine and Maria Elizabeth to escape from their parents to the protection of the Swedish royal court, which became a scandal in contemporary Sweden. He succeeded his brother Adolph John II as Count Palatine of Kleeburg in 1701, and his cousin Charles XII, King of Sweden, as Duke of Zweibrücken in 1718. The king's death also made him one of the eligible candidates for the Swedish throne. From 1720 until 1725 he moved his residence to a palace, Schloss Zweibrücken, built by Jonas Erikson Sundahl. Gustavus Samuel Leopold died in Zweibrücken in 1731 and was buried in the Alexanderkirche. As the last male member of his branch of the House of Wittelsbach, his territories were inherited by Christian III, Count Palatine of Zweibrücken-Birkenfeld. He competed for the Grand Mastery of the Sacred Military Constantinian Order of Saint George, whose obscure magisterial dynasty was going extinct in the late 17th century, and whose grand mastership had been transferred to Francesco Farnese, Duke of Parma in 1696. In the annals of that chivalric institution and of the Vatican, Gustav is referred as a Duke of Bavaria. Gustav failed in his aspirations, and the grand-mastership was confirmed in 1701 by the pope to be hereditary in the House of Farnese and its successors. The Farnese duke was later succeeded in the position by his nearest male kinsman, the future king Charles III of Spain. Duke Gustav had the baroque Residenz of Zweibrücken constructed in the 1720s, the Swede Jonas Eriksson Sundahl being the builder. In Swedish politics, Duke Gustav was the last male of the line of his paternal grandmother, Katarina Vasa. Upon the death of his cousin King Charles XII, Gustav of Stegeborg then became one of the eligible candidates for legitimate succession to the thrones of Sweden and of the grand duchy of Finland. He would have become king Gustav III, had he succeeded. However, no strong faction or party in Sweden took up his cause, and his succession rights are not much remembered by history. Instead, his cousin Ulrica Eleonora managed to become the Swedish queen regnant. Duke Gustav died during the reign of Frederick I of Sweden. His Swedish rights were inherited either by his nephew Charles Adolf Gyllenstierna, count of Ericsberg, or his sister, Countess Palatine Marie Elisabeth of Kleeburg, or their cousin, Charles Frederick, Duke of Holstein-Gottorp.
Marriage
On 10 July 1707, Gustav married Countess Palatine Dorothea, daughter of Leopold Louis, Count Palatine of Veldenz. The marriage remained childless. On 13 May 1723, he morganatically married Louise Dorothea von Hoffmann at Zweibrücken, a daughter of Johan Heinrich von Hoffman by his wife, Anne Chocq. She converted to Catholicism in 1723 and was raised by the Holy Roman Emperor on 3 March 1724 to the title Countess von Hoffmann. They also had no children.
