Here’s some insight into J. K. Rowling’s perspective on tyranny, in the words of Albus Dumbledore, speaking of the arch-villain of the series:
Voldemort himself created his worst enemy, just as tyrants everywhere do! Have you any idea how much tyrants fear the people they oppress? All of them realize that, one day, amongst their many vicitms, there is sure to be one who rises against them and strikes back! Voldemort is no different! Always he was on the lookout for the one who would challenge him. He heard the prophecy and he leapt into action… (Harry Potter and the Half-Blood Prince, p. 510).
My most immediate thought upon reading this passage was the account of King Herod in the book of Matthew.