1502:

Cesare Borgia executes rival leaders

The infamous Cesare Borgia, son of Pope Alexander VI, sought to create a united government over central Italy with himself as monarch. However, the Orsini family headed up a strong league of nobles who stood against him. Borgia acted with great finesse and no scruples: even while he built his own army of loyal soldiers, he convinced the Orsinis and their associates that they had nothing to fear from him. He invited several leaders of the opposition to his castle, Senigallia, where he imprisoned Francesco Orsini, Paolo Orsini, Oliverotto da Fermo, and Vitellozzo Vitelli, all of whom were leaders of the Orsini faction. The latter two were exectued -- or, more precisely, murdered by strangulation.

Already in control of Romagna, Perugia, and Urbino, Borgia now stood poised to conquer central Italy. However, his fortunes changed dramatically when his father died. After spending two years imprisoned in Spain, he joined his wife's brother, the King of Navarre, in a campaign against Castile and was killed in battle.

1491:

Jacques Cartier

Jacques Cartier was a navigator of some repute when he was selected by Philippe de Chabot to head an expedition to America in search of a northwest passage to the orient. On his first expedition in 1534 he discovered Magdalen Island and Prince Edward Island. Landing at Cape Gaspé, he claimed the mainland for the king of France. On his next expedition he explored Lake St. Peter and came upon a fortified settlement at the base of a grand hill, which he called Mount Royal and which became the city of Montreal.

Cartier served as a technical advisor in nautical matters and as a Portuguese interpreter. He wrote the book Discourse du voyage fait par le capitaine Jacques Cartier aux terres neufves de Canada, which was not published until 1598.

1514:

Andreas Vesalius

A physician of great ability and vision, Vesalius is perhaps best known for writing the first truly accurate book on the human anatomy, De Humani Corporis Fabrica. He learned by dissecting human cadavers (instead of studying lower life forms, as his contemporaries did) and for that he was sentenced to death for grave-robbing by the Inquisition. The sentence was commuted by Holy Roman Emperor Philip II to a pilgrimage to the Holy Sepulchre.

1384:

John Wycliffe