Who fought against the protestant reformation?

The Catholic Church and its leaders, particularly Pope Leo X and later Pope Paul III, fought against the Protestant Reformation. They sought to counter the reforms initiated by figures like Martin Luther and John Calvin through the Counter-Reformation, which included the Council of Trent and the establishment of the Jesuits. Additionally, various monarchs and political leaders aligned with the Catholic Church sought to suppress Protestant movements to maintain religious and political unity within their realms.