Every hero needs a villain. It's just the natural order of things. Now, if you can bend steel beams with your bare hands, or leap tall buildings in a single bound, then nine times out of ten you'll be facing someone who's as equally powered as you.
But not always.
What if your foe only has their smarts, and a vicious streak a mile wide, with which to bamboozle you? Is it even possible for a mere mortal to face someone with godlike potential, and to give them a good kicking, or at least a run for their money?
There's something to be said for super-powered foes, whether they are massively intimidating like Galactus, or unstoppable killing machines like Doomsday, but when the main villain is just a (barely) normal, individual, it's something everyone can relate to.
These are the reasons that these bad guys and girls tick the boxes when it comes to breaking the law. They're conniving, manipulative, and often rather ingenuous. They manage to find a way to repackage and redefine their villainy all the time, and more than a few have succeeded when coming to blows with their more heroic counterparts.
That's why they're so universally loved, but there are some non-powered heroes who are better than others.
10. Harley Quinn
First showing up in the exceptional Batman: The Animated Series episode "Joker's Favor", Harleen Frances Quinzel was nothing more than a sidekick and punching bag to Mistah J. It would take her a while to find a place for herself in the pantheon of DC villains, but when she finally did she would become a constant thorn in the Dark Knight's side - as well as in that of the Joker's.
Her team up with her best-friend and later romantic partner, Poison Ivy, would see them pull off a string of capers that would leave Gotham's rich and privileged with highly inflated insurance policies, as the two stole anything that wasn't nailed down.
This strategy would actually end up vexing the Dark Knight, as her unpredictability always meant that he was never quite able to get a grip on her actions.
As the years passed she would be transformed into more of an anti-hero, with her face plastered on merchandise and comic books left, right and center, but there is no doubt that at her criminal peak, Harley Quinn was one hell of a villain.