Does anyone watch Castle?
Some spoilers for an episode ahead.
So in one episode a man is found murdered inside a pizza oven. At first they think it's one of the other pizza places that did it. Turns out the guy was a reported that was doing a piece on the pizza wars but he uncovered something more sinister in the works and it got him killed, drug trafficking. It turns out that the reporter, named Burns, ironically enough, was on the trail of a legendary criminal named Caballo (pronounced cabalo, the Italian for horse) who was more myth that fact. Stories said that he was ruthless and brutal. They find that a man who Burns thought dead had faked his own death (who was put in a barrel and burned alive as a hint of Caballo's brutality) was the one who killed him and that it was possibly he who was Caballo. They find that a heroin house and track down the real estate agent to see if she knew anything. When they get to her house they hear a scream, they knock the door down but Caballo escaped. The real estate agent confirms their suspicions, Caballo is the man they suspect and he was using her to purchase real estate properties to use for their packaging and distribution of heroin. At the end of the episode they kill the suspect but Castle and Becket start putting two and two together and realize that that man couldn't have been Caballo, that in fact the real estate agent, who they just let go, made more sense. They catch her at the elevator and begin the interrogation. She never confesses but it is made clear that she is, in fact, Caballo.
This episode was rather fun. The suspect wasn't just a pretty young woman, she was clever enough to use that fact to help her hide her identity and brutality of her nature. It's a good way to display how the gender doesn't even enter into the equation of how evil that person is, only in our perceptions of them. While it wasn't heavily touched on in the episode the viewer dismisses the woman on her acting and looks simply because, again, she is young and pretty. Never judge a book by it's cover scenario on this one.
What I mean is that a villan shouldn't be so defined by their gender. Sometimes, like here, they add something to the equation but if you make the villan female out of a demand for it, 'we need a female villan,' it might take a toll on the character. The villan should be villinious regardless of gender and that is how I think a female villan should be approached.
PS- Another great villan, Mama from Dreadd. Not defined by her gender, just her evil doings.