Sir Thomas More, painted by Hans Holbein the Younger
Thomas More was a highly educated man who became Lord High Chancellor of England to Henry VIII in 1529. This made him a very powerful and influential figure. He was a staunch Catholic, however, so he fell out with Henry when he refused to help Henry to break away from the Catholic Church in order to marry Anne Boleyn. Because of this, Henry had him executed.
I think Thomas More is an interesting character because it's so hard to reconcile the good things he definitely did with the bad things he may have done.
In one way, he was a very modern man: he made sure that his daughters were educated to the same high level as his sons, which at that time was extremely unusual. He was also undoubtedly a man of principle: he refused to swear the oath of allegiance to Henry, against Rome, even when he realised that he would die for his silence. This was the version of Thomas More I learnt about at school, presented in the play and film, A Man for All Seasons.
However, the same principles that made him sacrifice his own life rather than go against his beliefs may also have led him to torture heretics he'd imprisoned in his own house (these were people who believed that the Bible should be in English so that it could be understood by everybody). This is the version of Thomas More we meet in Hilary Mantel's book, Wolf Hall.
It seems quite possible that Thomas More really did do this, although he always denied it, because he made no secret of the fact that he thought it was a good thing to burn heretics at the stake. For us today, it's very difficult to understand why Thomas More felt the Bible shouldn't be in English anyway, so burning people to death just for wanting that is impossible to comprehend.