Alexander Hamilton and Maria Reynolds
This one's a little less well-known -- it takes place at the dawn of the United States, during George Washington's presidency. The fact you might have not even heard of it demonstrates how our own view of leaders, present and past, has changed over the course of history.
Treasury Secretary Alexander Hamilton was 34 when he met Maria Reynolds, a married girl of 23 who claimed her husband James had abandoned her and her daughter [source: Weigant]. Hamilton gave Reynolds travel money, but picked up on some signals that she might be interested in more, and they began an affair that lasted three years.
But husband James was well aware of the situation. And in fact, he let the affair go on, extorting money from Hamilton for the duration of the relationship. Social protocol at the time was for the cuckolded man to challenge a duel, so the fact that James opted for blackmail is not only telling, but also -- as you'll see at the end of this story -- incredibly ironic.
Reynolds' con-man twists didn't end there: In a separate scheme, he was misusing benefits intended for Revolutionary War vets in some speculation that went south. Eventually, it blew up on both men, and Hamilton had a choice: Either admit to his creepy sexual arrangement, or implicate himself in the vet fraud.
Hamilton went to James Monroe (that's right, the fifth U.S. president) for advice, turning over Maria's love letters, which proved his innocence in the latter blackmail scheme. Monroe and his buddies in Congress decided to cover the whole thing up. But when Monroe sent the letters to Thomas Jefferson (you can't make this stuff up!), Jefferson went tattling all over town.
In the end, a muckraker named James Thomson Callender got ahold of the letters, and took Hamilton down. Hamilton admitted his love affair and apologized, which helped but didn't completely restore his reputation. But this is where it gets weird: Deserting the sinking ship of her corrupt husband, Maria Reynolds eventually got Aaron Burr to represent her in the divorce. And yes, that would be the same Aaron Burr that eventually killed ... Alexander Hamilton. In a duel.