By Emily Feimster They're easy on the eyes and they can kick some major mutant booty - yes, we're talking about Hollywood's sexy sci-fi actresses! From the days of Jane Fonda as Barbarella and Nichelle Nichols as Lietenant Uhura, on through Sigourney Weaver in "Aliens" to "The Matrix's" Carrie-Ann Moss to Gillian Anderson of "The X-Files," women have been a driving force in futuristic movies and television shows. Now that science fiction is at an all time high, check out which babes are giving these aliens a run for their money!

One of Hollywood's hottest actresses to grace the sci-fi community is Jessica Alba, who starred in the short-lived, but highly popular "Dark Angel." Though she's gone on to reach A-list status, she hasn't forgotten where she came from having recently starred in "The Fantastic Four" as an astronaut who gained superpowers after cosmic radiation exposure. She and her "Fantastic" co-stars are already set to reprise their roles in 2007.

Taking Alba's place as one of television's most popular sci-fi stars is "Battlestar Galactica's" Tricia Helfer, who has been hailed by critics as the new pin-up girl of science fiction. She plays Number Six on the thriller, which has been achieving increasing acclaim since its 2004 launch. "What I like most about Number Six is that she has a mixture of everything. She's tough. She's not just a girl walking around in a red dress. She's definitely got a lot more at stake," says Helfer, who made the transition from modeling to acting four years ago. "In fact, the show has quite a few strong female characters so a lot of the audience is female, which I hear isn't typical for science fiction shows."

Helping to bring in those female fans is Helfer's Korean co-star Grace Park, who plays Lt. Sharon "Boomer" Valerii. Having come up the ranks by also appearing on "The Outer Limits" and Alba's "Dark Angel," the Los Angeles-born actress was named number 81 on the Maxim magazine "Hot 100 of 2005" list. "Battlestar Galactica" also also boasts former "Xena: Warrior Princess" star Lucy Lawless as D'Anna Biers.

You can't get much hotter, though, than "Smallville's Kristin Kreuk and Erica Durance. Kreuk, who stars as Clark Kent's love interest Lana Lang on the WB show, came in at number one on Femme Fatales' 50 Sexiest Women of the Year list. It certainly didn't take fans long to accept her co-star Durance, who joined the cast in 2005 as Lois Lane. Due to her character's overwhelming popularity in season four, Durance was made a series regular. As if she doesn't deal with enough superpowers on "Smallville," she's also currently filming the sci-fi thriller "The Butterfly Effect 2." Yes, she's what we'd call a science geek's fantasy woman, but sorry, guys, she's taken!

There's no shortage of fantasy girls when it comes to science fiction movies. Just think Natalie Portman as Queen Padme in "Star Wars" and Jada Pinkett in "The Matrix Reloaded." Fans certainly thought they had it made when they heard Oscar winner Charlize Theron would be starring in "Aeon Flux." However, Oscar or not, even she couldn't make this one a hit.

Milla Jovovich's new release, "Ultraviolet," has also received mixed reviews, but ironically she's still being called the new sci-fi IT girl by her big fans in the industry. We guess it helps that she is about to start filming the third installment of her "Resident Evil" franchise. And let's not forget her form-fitting body suits! Those can make or break any science fiction movie. Just ask the cast of "X-Men: The Last Stand," which will again boast not one, but THREE mutant mamas in tight fighting clothes. Yep, there's Halle Berry, Rebecca Romijn, and Famke Janssen. We can tell you're drooling already!

Of course we can't leave out some of the Sci-Fi Network's other leading ladies - Amanda Tapping of "Stargate: SG-1," who first got her sci-fi feet wet with "The Outer Limits" and "The X-Files." Rachel Luttrell, best known as a member of a fallen alien world on "Stargate: Atlantis." And last but not least, Luttrell's co-star Torri Higginson, who takes great pride in playing the woman in charge on her hit show, Dr. Elizabeth Weir.

Says Higginson of her character, "What I originally liked about her most is that I thought her politics were sort of similar to mine, which is fun to play in a genre which usually kind of embraces the whole Manifest Destiny ideas, which isn't one of my politics," she tells us. "I liked that she was anti-military and really fought for a universal, global community. But when you're dealing with aliens that want to suck the life out of you, politics shift a bit." Indeed.