6. The Original Series "Turnabout Intruder"
A psychotic ex of Captain Kirk returns, pissed that women aren't allowed to serve as starship Captains. In a plot typical of a mad scientist, hell-bent on revenge, she decides to take over Kirk's body and use him to exact her vengeance on the sexist Starfleet. In watching this episode, I find it more likely she was passed over for a captaincy not because she's a woman but because she's mentally unstable and can't come up with a good plot for her revenge. Personally, I believe the producers of Enterprise chose to cast the NX-02 captain as a woman just to prove that Janice Lester really was just a psycho ex-girlfriend. Of course, we already knew that.