King Gustav I of Sweden, also known as Gustav Vasa, reigned from 1523 to 1560. He is often credited with founding the modern Swedish state after leading a successful rebellion against Danish rule. His leadership helped establish Sweden as an independent nation, and he is remembered for his efforts in consolidating power and reforming the government. Gustav I was also instrumental in the Protestant Reformation in Sweden, promoting Lutheranism and reducing the influence of the Catholic Church. His reign marked significant changes in Swedish society, including the establishment of a centralized monarchy and the development of a national identity.