Or Kristen Bell.

I love most of her films, she's a great actress who is perfect for almost any role

I picked Helena Bonham Carter because she is a great actress, she can play some roles that others can't. Sarah Michelle Gellar just seems wrong to me. Madonna's too old.

Helena
Cate
Naomi
Scarlett
Madonna
Sharon

Helena Bonham Carter is a good actress, but I don't see her as fitting the role. Don't mind me though, as I don't really know that much about Harley Quinn.

She already knows how to do all the tumbling and has the agility. I mean look at Buffy!

Helena Bonham Carter is a phenomenal actress, with a wide range of character. She is great at playing villians. Sarah just isn't right, in films I find Sarah annoying and I think Helena suits the role best. Also, Helena is a waaayyy better actress than Sarah.

I kind of have to agree with some of the posts above. Helena would be better in the part than Sarah. I picked Cate Blanchett because she too is good at villian parts. I am torn between Helena, Cate and Madonna.

Helena is wild at villians. She'd make Harley into a wild animal that just got out of the zoo! She'd rock in this role and I'd bet my life on an Oscar!

She could so pull it off.