Sarah Rees Brennan has an excellent, lengthy post about why female characters in fiction so often fell short in ye olden days, why they still often do, and some strategies to consider when writing them. Plus, it’s funny:
PETER THE MAGNIFICENT: My brother Edmund is no longer a friend to Narnia.
ASLAN: Oh that’s a pity.
PETER THE MAGNIFICENT: All he thinks about parading around in nylons and lipstick!
ASLAN: … Say what?
PETER THE MAGNIFICENT: DON’T ASK ME TO TALK ABOUT IT!
Male villains tend to be much less sexualised. It was never suggested, for instance, that Sauron or Saruman was sexy. (If you just got an image of a big flamey eye doing a booty dance, I am truly sorry.)
We won’t discuss the movie visual of Sauron in this context, among, y’know, polite company.