- It's often forgotten that Harley is, in fact, a psychologist and very smart. In the Gotham City Sirens story arc "Hell Hath No Fury", her expertise gets shown off MAGNIFICENTLY when she breaks into Arkham using marbles and a bomb (though she may have been able to do it without the bomb, she didn't want to take that chance), gets the remote to shut down the debilitation system with a fabric flower and Joker gas (revealing in the process that she had planned for the possible necessity of using such a trick on Sinner from way back when she was still working at Arkham), starts a Prison Riot by exploiting what a crowbar means to Clayface, and then gets the head of security to let her into Joker's cell in order to kill him by talking the sergeant through the real circumstances behind his infant son's death. That last one might possibly have been a story she made up, but even if it was, the whole thing is a beautiful showcasing of Harley's intellect.
- A Meta example for the character herself: Originally created by the Batman: The Animated Series as a one-off gag character so the writers could use a Basic Instinct joke, Harley quickly rose to become one of the most popular Rogues in Batman's lineup and from there turned into one of the most popular Anti-Villain characters in the history of the DC Universe.
- The origin of the Gang of Harleys comes from an overwhelmed Harley having an epiphany almost no other hero might: recruit some help. True, she does it in typical Harley fashion but it's pretty good foresight.
- Issue #25 of her New 52 solo is a big one for Harley, wherein after breaking into Arkham to get Mason out, she takes the time to get back at the Joker (who, wouldn't you know it, was in the cell right next to Mason's) by beating him to a pulp for all the crap he put her through. Even more awesome is the fact that his words can't sway her back to his side anymore. When he manages to get her to kiss him, she rips his lower lip off with her teeth. You go, girl.
"I'm not yer toy anymore. Unnerstand? You did mean something ta me one time, but that time is over. If I ever hear you or see you again...if ya ever mess with my family or my friends...I'm not gonna be as nice as I was today, an' I'll finish yer alabaster ass for good! Now, do yerself a favor and fer once in yer miserable life, say nuthin'. No chattin'...no chortlin'...just lie there an' bleed."