I don't actually need the leading lady to be a 'villain' or an 'evil' character, but more like
A. the one doing the revenge towards people who hurt her or wronged her,
or,
B. a criminal, a scam artist, etc.
The other important thing is a guy who either tries to help her, redeem her, cares for her and feels sorry for her, tries to make her see reason and so on. (He can be the one she's taking revenge on, or just anyone. xD)
My absolute favourite drama like this is "Guilty Akuma to Keiyakushita Onna" where the leading lady is taking revenge, the leading guy is a cop who sympathizes with her and tries to help her.
Any recs would be awesome. :)