Ferdinand I, Holy Roman Emperor (1503-1564) was a significant ruler in the Habsburg dynasty. He became Emperor in 1558 and was known for his efforts to maintain peace within the Holy Roman Empire during a time of religious conflict. Ferdinand was also the King of Bohemia and Hungary, and he worked to strengthen the Habsburg influence in Central Europe. Ferdinand I was a devout Catholic and played a crucial role in the Counter-Reformation, supporting the Catholic Church against Protestant movements. His reign was marked by diplomatic efforts, including treaties that aimed to resolve tensions between Catholic and Protestant states within the empire.