When the big question of who the most frightening Batman villain is inevitably comes around in nerdy conversation, most people’s go-to answer is the Joker. It’s a pretty good answer. It was my answer for a very long time until I started doing deeper dives and expanding my reading. Once I did, I realized that the most terrifying Batman villain—yes, even more frightening than Scarecrow, Dollmaker or Professor Pyg—is Harley Quinn.

Now, I know some readers are going to want to argue that Harley Quinn is derivative of the Joker. That’s she’s just another off-shoot of his persona whose very existence could never have happened without his inception decades earlier. That’s a very fair point. I’m certainly not going to argue that the point of conception for Harley was as anything other than “Joker’s Sidekick” when she first appeared on Batman: The Animated Series a quarter of a century ago. However, I will contend that Dr. Harleen Quinzel and her adorably psychotic alter-ego are far more frightening than the Joker ever thought about being.

A large reason I believe this is because of her particular background and training. The Joker succeeds as a villain because he is shrouded in mystery, and by contrast, Harley Quinn outstrips him because of the details that we do know about her. She transcends simply being a cracked personality or unstable mind. Dr. Quinzel built her life as a master of the human brain—the type of person who can crawl inside any given person’s psyche, make a home there and glue the pieces back together. You could even argue that it was precisely because she was so good at that job that she found herself entranced with the Joker and his deeply disturbed mind in the first place. If there was ever a holy grail of depraved minds to challenge a psychiatrist’s abilities, it would be the Joker’s. After healing a mind like that, everything else would be child’s play and a pretty big letdown. Why not make a permanent home there?

This skill of hers—which ultimately brought about her baddie alter-ego—means that after a psychological examination, Harley Quinn is able to discern what is most fragile about any individual she faces. Harley may be known for whacking people in the face with a giant mallet, but the possibility of being psychologically destroyed by her is far, far more destructive in the long run. (Though I’m sure being whacked in the face with a mallet is no picnic either.)

That chaos and disorder that Harley Quinn can bring to any master plan or criminal undertaking? It’s psychologically motivated to shatter the senses and put the victim as far back on their heels as possible while giving Harley and her goons multiple windows of opportunity to accomplish their tasks at hand. (Harley’s got amazing goons in the Karl Kesel HARLEY QUINN solo series that you must read if you never have!)

Now, since her inception, Harley Quinn has undergone some fairly distinct personality changes and character evolution. She is presently enjoying the status of antihero, burgeoning on true heroism depending on the storyline and depending on the day. The most interesting thing about this shifting of her status quo is how Harley can unleash the same set of skills on the bad guys and gals that she used to align herself as effectively as she used to on innocents. The character as she exists in the Injustice video game and tie-in comic universe is a perfect example of this. She’s able to harness her particular set of skills in order to set former allies, like the Joker, back on their heels. Or at the very least to distract them while another character she is allied with throws the punch.

This sense of biting psychological pain combined with traditional super-villainy is something that some readers might want to also credit Scarecrow with. While that’s true, I would contend that what Harley does is more frightening because it’s not all tied to a chemical. It’s more unhinged, thereby more dangerous, because you never know what you are getting into with her. With Scarecrow it’s always going to be a gas. Grab a gas mask and that’s the lion’s share of the work out of the way. Congratulations, you’ve beat the Scarecrow!

Harley has the unique ability to harm a victim (or a foe, if you’d rather frame it from that perspective), on a number of different levels and package that threat unpredictably. She does something that no one else is doing in the DC Universe and she can go farther and cut deeper than anyone else in the Multiverse. In this way, she is singularly qualified to be the scariest person that a character could go up against.

I would encourage readers to not dismiss the very real threat that Harley Quinn presents just because she is a beautiful, usually over-the-top woman in a colorful costume. This presentation is just another part of her evil genius. If you are thinking, “How could someone so cute be so dangerous?” Well, then she’s already got the upper hand.

Ashley V. Robinson writes about Rebirth for DCComics.com and covers The Flash for the #DCTV Couch Club. Look for her on Twitter at @AshleyVRobinson.