Recently we were daydreaming about Megan Fox (as we're wont to do) when it hit us: She is, by default, one of today's top sci-fi-movie babes. Where are the kick-butt heroines of yore -- the Ripleys and Leias who would sooner blast you than entertain your pathetic attempts at flirting? In honor of Fox's midriff-baring performance in "Transformers: Revenge of the Fallen," we're counting down our favorite sci-fi babes, past and present. Nerds, set your phasers to "stunning." (And keep your pants on.)

10. Megan Fox
Though we're hard-pressed to think of anything else Fox has done, her role as SexFormer-5000 in "Transformers" definitely left an impression. With her transformable cut-offs and laser eyes, Fox is -- wait, Megan Fox is human? She's not a robot designed specifically for titillation? But her acting is so robotic.
9. Sigourney Weaver
Thirty years since "Alien" and Weaver still has the monopoly on strong female sci-fi heroes. From "Ghostbusters"'s Dana Barrett to her cleavage-y turn in the still hilarious "Galaxy Quest," Sigourney is the Brando of the genre. It's a testament to her lasting appeal that we can't think of anyone who could legitimately replace her in the upcoming "Alien" reboot.
See the rest of our picks after the jump.

8. Angelina Jolie
While most of Jolie's heroines have been of the action-adventure variety, she makes it on the list solely for her eyepatch-wearing turn in "Sky Captain and the World of Tomorrow." (Boy, were they optimistic with that title.) We can't even tell you who else was in that movie, so powerful was the ray of hotness that emanated whenever Angelina was onscreen, like some sort of sultry Nazi stormtrooper dominatrix.

7. Jane Fonda
Though she only made one major sci-fi movie, it's hard to top "Barbarella." Few actors could work opposite an orgasm-producing device and keep their dignity. Fonda went on to become one of our most acclaimed movie stars, but we'll always love her most when she looked like a sexed-up Fembot.
6. Zoe Saldana
With respect to the original Uhura, Nichelle Nichols, Saldana slipped into the go-go boots quite nicely for J.J. Abrams' "Star Trek" update. Pairing her with Spock is such a fun idea, we're actually looking forward to the sequel. The last time that happened with a "Star Trek" movie, it starred a shirtless Ricardo Montalban.
5. Natasha Henstridge
Besides being mind-meltingly sexy, it helps that Henstridge is naked for, like, 80 percent of the "Species" films. (She spends most of the second movie naked and strapped to a chair.) Thankfully for us, Sil seduces her prey, sometimes naked in a pool, before killing them with her spiky tongue. On the spectrum of sci-fi deaths, that sure beats a tiny alien tearing its way out of your stomach.
4. Everyone in "Serenity"
Joss Whedon, the man who gave us Sarah Michelle Gellar and Eliza Dushku, knocked it out of the park with "Firefly"/"Serenity" cast. And the best part is, they're all different types. Fancy a no-nonsense, take-charge leader? Look no further than tough-as-nails Zoe (Gina Torres). How about a doe-eyed killing machine? That would be future Terminator Summer Glau. Then there's "girl next door" mechanic Kaylee (Jewel Staite) and space hooker Inara (Morenna Baccarin). How this didn't become a long-running franchise is one of the universe's great mysteries.

3. Carrie-Anne Moss
While "The Matrix" look has not aged well (there's just something late-'90s goth-rave about all that leather), Moss is still supremely sexy brandishing a machine gun. Hey, Christopher Nolan: Here's your Catwoman. Moss could certainly use the mainstream exposure.
2. Milla Jovovich
Who could have guessed that the star of "The Return to the Blue Lagoon" would become one of our top action stars? Her role in "The Fifth Element" brought the phrase "Leeloo Dallas multipass" into the popular lexicon and inspired young women to parade around Comic-Con wearing nothing but tissue paper. And while her relationship with director Paul W.S. Anderson has produced about two "Resident Evil" movies too many, we still love her. (Though "Ultraviolet" was pushing it.)

1. Carrie Fisher
Empires may fall, Jar Jar may "meesa" us to death, but Carrie Fisher will always be there in that metal bikini. Millions of young boys imagined themselves swinging in, slashing Cookie with a light saber and rescuing Princess Leia from Jabba's fat fingers. And though the years have not been kind to Carrie, we'll always have our "Return of the Jedi" trading cards.

From the Web:
Top 10 Reasons Chicks Love Vampires
Reason one, they're into blood play. Just kidding. Maybe. (AskMen)
How and Why to Set Drinks on Fire
Just don't get it on your face. (AskMen)
Meet the Transformers
A guide to the robots. (Moviefone)

Meet the Ladies to Die For
Video game villainesses. (GameDaily)