Why has Hollywood had such a hard time finding the new Wonder Woman?

The answer is easy to "Dollhouse" star Eliza Dushku: "That's because I'm not available."

That was some of the discussion fans experienced during a panel honoring the strong women of science-fiction Thursday at San Diego Comic-Con. Dushku was joined by Sigourney Weaver from "Alien," Elizabeth Mitchell from "Lost" and the upcoming ABC series "V" and Zoe Saldana from the 2009 blockbuster "Star Trek." They took on a variety of questions from the 4,000 fans in attendance including how tough Weaver is.

Weaver called her iconic role of Ripley from the Alien series as a "very lucky opportunity." When she was filming the first "Alien," she had only focused on living one day at a time and was amazed she survived to the end of filming, both as an actress and the character she portrayed: Apparently Ripley wasn't supposed to survive the end of the first film.

Now she is considered one of the toughest characters on television. And even when she was ranked the second biggest bad-ass of all time by MTV, that still wasn't enough for her. "I think I could take him," Weaver said about Eastwood.

Mitchell, who plays a morally slippery character on "Lost," said she loves her character on the show because of her ambiguity, as it's more fun to play and more enticing to her as an actress.

"Liars are best when they are telling the truth because no one knows they are telling the truth," she said.

The biggest question on fans' minds, however, is whether Juliet will be back on "Lost" next season. The last we saw her, she fell down a shaft with an atom bomb, and detonated it in the final moments. Also, she's appearing in a new ABC series, "V," which is being prepped for a mid-season launch. Mitchell, however, was just as sly as her character on "Lost," saying whether she will remain is up to J.J. Abrams, and it would all depend on whether Jack's plan worked.

Right now, however, she is shooting the first season of "V," and will stay busy with that until if and when she returns to Hawaii for "Lost."

Saldana said she was in a humbling position that she hopes will inspire other women as Uhura in the latest "Star Trek" movie, but that as far as the battle of the sexes and whether women are still fighting the glass ceiling in Hollywood, she said she didn't think it should be seen as a battle. Instead, the issue is about educating people about what women are and what women can do.

"Choices women make to accept roles, interpret roles and revise those roles to make women more tangible and relatable," Saldana said. Something that might help however is having more women writers, directors and producers to create opportunities for a wider range of roles in women and television.

Hollywood men see women's sexuality as a threat, but Mitchell said women are multi-faceted and that, sexuality is but one weapon in their arsenal. Sci-fi is a fun place to showcase the variety of attributes a woman can offer. She also was excited to hear that for the first time in her career that she is now being considered "sexy." Women older than 30 are allowed to be more sexy and Mitchell said she really enjoyed that freedom.

Sci-fi investigates what it is to be human and it is a reflection of real life, Weaver said. Thus, anything goes and anything can happen. In sci-fi, there is not an effort to control women, and therefore woman have squeaked through and been allowed to portray more diverse roles.

So why is Wonder Woman so hard to cast then?

Saldana speculated that perhaps they are still looking for the right writer for such a complex character in order to capture al the many layers o the character. However, in order to get the laugh-factor back up, she finished by noting that it may also be hard to find an actress to fill the requirements for a "great rack and a great bum" like Wonder Woman has, Saldana said.

At one point, "Buffy the Vampire Slayer" and "Firefly" creator Joss Whedon was attached to the Wonder Woman project. He's not anymore, but both Weaver and Dushku -- the latter who stars in Whedon's latest Fox series, "Dollhouse" -- credited the man for writing such strong iconic roles for women in both film and television. Dushku said she was particularly grateful as she is allowed to portray the most diverse character that Joss Whedon has ever written, the "doll" Echo, which she said is "a perfect fit for me because of my [attention deficit disorder] kicks in."

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