What is the most interesting backlight story for an existing villain from an existing work of fiction?

Once I was on some redditor's profile and saw his post history, which had a link to an old post of his with the title above. I'm absolutely sure it was on r/AmItheAsshole, r/TrueOffMyChest, or a similar chambers, and the post itself was a poll with the options being Hans Gruber, The Riddler, Michael Scott, Keyser Soze, and The Joker.<br><br>Unfortunately that post is now a dead link and I have no idea who the redditor was. But I always thought that was a fascinating question.