Born on 10 November 1483 in Saxony, this German Priest took on an Empire - and won. Just like the defiant anti-war Peace Camp protesters, it would have taken a lot to push Luther off Parliament Square.
Incensed by claims that freedom from God's punishment of sin could be paid off with money, he confronted indulgence salesman Johann Tetzel with his Ninety-Five Theses in 1517. Tetzel is reported to have coined the rhyme - "As soon as the coin in the coffer rings, the soul from purgatory [also attested as 'into heaven'] springs."
Luther was having none of it. Within two weeks, copies of his theses had spread throughout Germany; within two months throughout Europe. Luther had begun to make serious waves in the Chritian world.
However, it was not until Archbishop Albrecht of Mainz and Magdeburg failed to reply to Luther's letter containing the 95 Theses that things really began to hot up.
Further enraged, Luther wrote to Pope Leo X. Leo's response was to send legate upon legate to condemn Luther as a heretic. Having been summoned to Rome, Luther openly denounced the Papacy, declaring that he did not consider it part of the biblical church. Luther was excommunicated by the Pope on 3 January 152.
Perhaps his finest achievement, other than standing up to the papacy's capital plunder, was in translating the Bible from Latin to the language of his people, and in so doing inspiring wide-spread translation and the refinement of modern-day German. For his legacy of game-changing feats, Luther has to be our number one.
Next: Henry VIII