The important people surrounding Martin Luther and the controversy over the Ninety-Five Theses.
Martin Luther was an Augustinian monk that started the Protestant Reformation. He sought to reform the Catholic Church and called to light certain abuses, specifically the selling of indulgences. He was eventually excommunicated from the Catholic Church, beginning the foundation of Protestantism.
Johann Tetzel was a Dominican monk who lived in Saxony. He was a prominent indulgence preacher, selling indulgences to help finance the construction of St. Peter's Basilica in Rome. It was his preaching that led Martin Luther to write his Ninety-Five Theses against indulgences.
Cardinal Albrecht of Brandenburg
Frederick the Wise
Frederick the Wise was the Elector of Saxony. As an imperial Elector, he was one of seven princes tasked with electing the Holy Roman Emperor. His capital was in Wittenberg, where Martin Luther was a professor. After Luther started the Protestant Reformation, Frederick the Wise protected him from prosecution by the church and Emperor. It was on the doors of his Castle Church that Luther supposedly posted the Ninety-Five Theses.
Charles V was the Emperor of the Holy Roman Empire. He was also King of Spain, whose empire included the southern half of Italy and many lands in the Americas. He met Luther at the Diet of Worms in 1521, where the Reformer was declared a heretic and outlaw. He remained a staunch opponent of the Reformation.
Pope Leo X
Pope Leo X was Pope when Martin Luther started the Protestant Reformation. He was from one of Italy's most powerful families, the Florentine d'Medici family. He became a Cardinal when he was 13 years old. This was due to a deal between Leo's father, Lorenzo d'Medici and Pope Innocent VIII. In return for making Leo a cardinal, Leo's sister would marry Innocent's illegitimate son. While pope, Leo X started an indulgence campaign to help finance the construction of the new St Peter's Basilica, which is still standing in Rome today. It was this indulgence campaign that caused Martin Luther to write his Ninety-Five Theses against the selling of indulgences. In 1520 Leo X issued Exsurge Domine, the papal bull banning Luther's works and threatening him with excommunication.