Alessandro de' Medici (1510 - January 6, 1537), Duke of Penne and also Duke of Florence (from 1532), ruler of Florence from 1530 until 1537, was the last of the "senior" branch of the Medici to rule Florence.
He was announced as the illegitimate son of Lorenzo II de' Medici, Duke of Urbino (grandson of Lorenzo de' Medici, the Magnificent), but many scholars believe him to be in fact the illegitimate son of Giulio de' Medici, later Pope Clement VII. The nickname derives from his features, and the possibility that his mother was a Moorish slave.
He was made ruler of Florence after Clement VII succeeded in returning control to the Medici in 1530, after a lengthy struggle. His rule was harsh, debased and incompetent. One relic of his rule is the massive Fortezza da Basso, today the largest historical monument of Florence.
Using Alessandro's debased nature to set a trap, his distant cousin Lorenzino de' Medici, secretly assassinated him, and then fled to Venice. The Palleschi discovered the murder before their opponents, and were therefore able to ensure that power then passed to Cosimo I de' Medici, the first of the "junior" branch of the Medici to rule Florence.