8. Alison Brie
As I mentioned earlier, Alison Brie, despite having supporting roles in Scream 4 and The Five Year Engagement, hasn't quite had her Hollywood breakthrough yet, which is a shame because she's a born star. All one has to do is watch an episode of the sitcom Community and then an episode of Mad Men, featuring her as a guest star, back to back to see her versatility. The other major reason I put her on this list is due to her role as Annie Edison on the aforementioned Community. I've realized that one of the great running character gags on the show is that despite Annie's sweet, straight A student exterior, she's actually quite bonkers. In fact her backstory involves her becoming addicted to Adderall in high school. which caused her to have a mental breakdown. Of course, this is all played comedically on the show but the type A personality who starts to become mentally unhinged is not too far off from Harley's psychological makeup. Brie is a wonderful comedienne and I think she could handle the darkly comedic persona the role requires. While Brie may be more suited towards a take on the character similar to that of the animated series, I'd love to see her go really dark for a role and knock us off our feet.