Well, just in time for his memorial, (today), St. Thomas a Becket has been voted worst person of the 12th century by historians surveyed by the BBC history magazine. The Independent explains:

As the patron saint of Roman Catholic secular clergy, Becket is nominated for the divisions he caused England. These seemed unlikely when the previously carefree and pleasure-loving courtier Becket became Archbishop of Canterbury in 1162. Yet once in office he became an ascetic prelate, devoted to the ecclesiastical hierarchy. In the schism which at that time divided the church, Becket sided with Pope Alexander II, who was devoted to the same strict hierarchical principles and, he dismay of Henry II, sought to exempt the church from all civil jurisdiction and secure unfettered control for the clergy. After returning from exile, he excommunicated the bishops who had crowned the king and an enraged Henry uttered his fateful plea to be rid of Becket. His subsequent murder brought Becket everlasting revenge on Henry. He was canonised and credited with martyrdom. A shrine to him remains at Canterbury.

Nominated by John Hudson of St Andrews University. He said: "He divided England in a way even many churchmen thought unnecessary."

To be fair, the worst person of the 16th century was Titus Oakes, an anti-Catholic fanatic…