DR. AKI ROSS, the young female protagonist of ''Final Fantasy,'' Columbia Pictures' new science-fiction epic, has the sinewy efficiency of Sigourney Weaver in ''Alien'' and the curves of Julia Roberts in ''Erin Brockovich.'' But when Aki arrives at the megaplex on July 11, audiences are as likely to be struck by the anxious furrows that flit across her brow and the scattering of moles on her neck. To be sure, Aki's flaws are minimal; they register just enough to render her human.

That achievement is remarkable considering that Aki is no more than a computer animation. She stars in a movie that is being hailed for its technological breakthroughs -- doing for humans what Pixar did for toys and Steven Spielberg did for dinosaurs. Aki is the most realistic of a new generation of computer-generated bombshells turning up in films, fashion and advertising.

As proof of their eerily convincing appearance, they have established personas of their own and are able to migrate from one medium to another, building virtual careers much like flesh-and-blood beauties. Last month, Aki edged out dozens of real-life models and starlets to become the cover girl on Maxim's ''Hot 100,'' a supplement to the babes-and-brews magazine. The same computer wizards who rendered her digitally in the estimated $100 million ''Final Fantasy'' stripped her down to a string bikini for Maxim.

Then there is Webbie Tookay, the latest lithesome discovery of John Casablancas, the founder of Elite Model Management, which shaped the careers of Cindy Crawford and Naomi Campbell. Webbie exists only in cyberspace, the creation of a Swedish animator named Steven Stahlberg, but that didn't hinder her from posing for a feature in Details in October, 1999, and a new Nokia phone advertising campaign in Latin America.