The Radical Reformation represented a response to perceived corruption both in the Catholic Church and in the expanding Magisterial Protestant movement led by Martin Luther and many others. Beginning in Germany and Switzerland in the 16th century, the Radical Reformation gave birth to many radical Protestant groups throughout Europe. The term covers Radical Reformers like Thomas Müntzer and Andreas Karlstadt, the Zwickau prophets, and Anabaptist groups like the Hutterites and the Mennonites.

Thomas Müntzer was a German preacher and theologian of the early Reformation whose opposition to both Martin Luther and the Roman Catholic Church led to his open defiance of late-feudal authority in central Germany. Müntzer was foremost amongst those reformers who took issue with Luther's compromises with feudal authority. He was a leader of the German peasant and plebeian uprising of 1525 commonly known as the German Peasants' War.