Delenn, Babylon 5. Her people's leader, until the job to be done required that she give up all her power and do something incredibly brave. She kicks ass from season 1 until long past the series' end.
Scully, The X-Files. Because rationality and a skeptical approach are the engines of scientific progress. And educated, thinking women are cool. I wanna be Scully when I grow up.
Ripley, Alien. Normally women in horror movies are the ones to die, but not Ripley. She turns the convention over. She keeps her head and saves her cat.
Granny Weatherwax, Discworld. Because not all of us have the skills or the opportunities to use guns and swords, but all of us can use headology to wrangle the world into place.
Buffy, Buffy the Vampire Slayer. "Giles, I'm sixteen years old. I don't wanna die." And she goes in to face the Master anyway. That's what a hero does. Keep on kicking demon ass, Buffy.