Martin Luther was a leader of the Reformation in?

Martin Luther was a pivotal leader of the Protestant Reformation in the early 16th century. His actions, particularly the posting of the Ninety-Five Theses in 1517, challenged the practices of the Catholic Church, especially the sale of indulgences. Luther's emphasis on salvation by faith alone and the authority of scripture as opposed to church tradition reshaped Christianity and led to the establishment of various Protestant denominations. His work laid the foundation for significant religious, cultural, and political changes in Europe.