Who was the leader of Sweden in the Great Northern War?

The story behind the answer

Charles XII was Sweden’s warrior-king during the Great Northern War (1700–1721). Ascending the throne at 15, he won stunning early victories like Narva (1700) and campaigned across Poland and Saxony. But his invasion of Russia ended disastrously at Poltava (1709), marking the decline of Swedish great-power status and the rise of Russia in the Baltic. The war concluded with treaties such as Nyst