There are many, many bad girls who do good in speculative fiction. I will just mention a few and I welcome comments about other "bad girls" in science fiction, fantasy and horror.
The novels and short stories written by Octavia Butler overflow with the baddest (meaning good) girls. I could write a Ph.D. thesis on the portrayal of strong women in Butler's works. If I had to choose one, it would be Anyanwu in Wild Seed. Originally published in 1980, Anyanwu was a shape shifter, who watched over and protected her family for generation after generation. She could not die, but she frequently mourned the deaths of her children, grandchildren, great-grandchildren, great, great great and so-fourth. She celebrate births. She nurtured all of her children to help them achieve the best they could during their brief lives of only 40 to 70 years. Then, she met the ultimate bad boy, Doro, who also could not die. He lived for thousands of years. But that is another story.
In the TV sci-fi, FireFly, first mate Zoe Washburne (Gina Torres) is a veteran "Browncoat" of the Unification War, a failed attempt by the outlying worlds to resist the Alliance's assertion of control. She is loyal to the captain of a ship of smugglers and has a husband, a dashing pilot, that she fiercely protects. In a bar fight, you want her by your side. When locked in a desperate space battle with hostile aliens, she will win. The TV series lasted only a few seasons and the following movie, "Serenity" was awesome; but the wild west in outer space meme was getting thin. However, we will always appreciate Zoe as the hard-fisted, tender hearted hero of the galaxy. She has a long list of credits including the campy, Cleopatra 2525 TV show which was fun to watch but sadly lacked any intellect.
Storm is my personal favorite among all fictional female heroes. Unfortunately, the cinematographic portrayal of Storm by Halle Barry (a great actor) was weak and underplayed. But in the comic book versions, Storm rocked the planet. For instance, read the story when she married Black Panther the king of an African and technologically advanced society. She protected a continent and became the leader of the X-Men. But Storm is more than a mutant, she is an African Goddess with tremendous powers like Thor, the Thunder God. Storm was one of the first black comic book characters (1975), and the first black female to play either a major or supporting role in the big two comic book houses, Marvel Comics and DC Comics. If the big money, Hollywood assholes were smart and followed simple greed instead of racism and sexism, they would produce a big budget movie based on Storm, Ororo Munroe, an African superbeing. We are tired of Batman, Superman, Spiderman and Iron Man.
