Peter III of Russia
He was born in Gottorf Castle as the elder son of Duke Christian Albert of Holstein-Gottorp and Princess Frederica Amalia of Denmark. He was married on 12 May 1698 to Princess Hedwig Sophia of Sweden and they had an only child, Charles Frederick, who eventually fathered the future Tsar Peter III of Russia, therefore making Frederick a patrilineal ancestor to all Russian emperors after Catherine II.