How Harley Quinn Became DC Comics' Most Successful Villain

No one could have predicted that Birds of Prey character Harley Quinn would last beyond her first comic appearance, much less become the title character in a series that cracks the best-seller charts every month, not to mention her own DC movie.

Harley Quinn (DC), Heroes Wiki

Harley Quinn #22 - #27 review

How Harley Quinn Slowly Turned Its Protagonist Into a Hero

Harley Quinn (DC Comics), Batman Wiki

DC's Harley Quinn series kills a lot of characters for a superhero show - Polygon

Who is the best Harley? All the Harley Quinns, ranked

Harley Quinn and Poison Ivy: The Greatest Partnership

Harley Quinn, DC Universe Online Wiki

Is Harley Quinn a Villain or a Superhero?