You may have never heard of Albrecht of Bradenburg, but he is an important part of the Reformation story. He was made a cardinal at the age of 28. To pay for the vestments and rights that came with this position and the Electorate of Mainz, he had to borrow thousands of ducats. He did not have the funds to pay this back, so he obtained permission to sell indulgences from Pope Leo X. Albrecht obtained the services of John Tetzel to sell the indulgences, and the rest is history.
Martin Luther wrote his famous 95 Theses in reaction to the selling of the indulgences. And on October 31, 1517, not only did he nail a copy to the door of Wittenberg Church, he sent Albert a copy. Albert forwarded the theses to Rome, suspecting Luther of heresy. And the Reformation began.