Gotham: 10 Best Batman Villains Not Yet Used On The Show
7. Harley Quinn
Considering this character's meteoric rise over the past 25 years, it is almost unthinkable that a young Harley Quinn hasn't appeared yet in an episode of Gotham.
With her eclectic style and boisterous personality, Harley is, without question, one of the most entertaining of Batman's rogues. And while her relationship with The Joker is inherently problematic, a potential appearance on Gotham would likely take place long before they even meet and before she was even "turned", leading to an intriguing spin on the character.