WHO WOULD BE JULIA

Once, the Hollywood-exec mantra was ''Get me another Tom Cruise.'' Then Brad Pitt heeded the call. Now the prayer has become ''Get me the new Julia Roberts.'' Not that there's anything wrong with the old Julia, mind you. But after 13 films, Roberts has outgrown ingenue roles-even if she is only 27. Throw in her $12 million price tag, and the need for an heiress-apparent becomes clearer. Of the legions of fresh faces who have the potential to become the new Julia (read: who can open a movie), three names emerge: Julia Ormond ''I want to make my mark, and master this business in some way,'' says Ormond, 30. In many ways the British-born newcomer already has. Best known for starring in Young Catherine on TNT, she racked up two impressive credits (Legends of the Fall and the upcoming First Knight) before landing the title role in Sydney Pollack's remake of the Audrey Hepburn classic Sabrina, due in November. Lately, however, Ormond's received more attention than she wants. First she made the Hollywood trades when she switched agencies, moving to CAA (which will surely up her rates from the $300,000 she reportedly got for Sabrina). Then she dropped new publicist Lois Smith of PMK for Nancy Seltzer, who, coincidentally, reps Roberts. And just last week she was the subject of an unflattering profile in The New York Times Magazine. Still, Ormond has many supporters, from Legends costar Pitt to Miramax cochairman Harvey Weinstein. Weinstein, in fact, agreed to distribute her Brit indie film, Captives, and has reportedly invited Ormond to join the cabal of insiders-Quentin Tarantino among them-who offer him feedback on scripts. Currently battling rumors of friction on the set of Sabrina, Ormond remains wary of Hollywood. ''(My) first role on stage in the sixth grade was playing a lamb who went to slaughter,'' she said at a Legends press junket, ''and it hasn't changed. That's a joke.'' Julianne Moore Although her on-screen romance with Harrison Ford was dropped during the filming of The Fugitive, Moore's been gaining steam for years. A graduate of the soap opera As the World Turns (along with Meg Ryan), she recently turned heads with a bottomless nude scene in Robert Altman's | Short Cuts. In Nine Months, due July 14, she's front and center as the pregnant mate of Hot-Brit-of-the-Moment Hugh Grant, with Robin Williams playing her wacko gynecologist. Rather than compare her to Roberts, however, Nine director Chris Columbus suggests, ''She has the potential to be the next Meryl Streep. New York Times film critic Janet Maslin said, 'She brightens any film she's in.' And I rarely agree with Maslin.'' The break for Moore, who's also appearing in Todd Haynes' art film Safe, should come in the Sylvester Stallone-Antonio Banderas adventure Assassins, due in October. (Her $1 million payout is a sign she's come up in the world.) Especially when you consider what happened to a recent Stallone sidekick, namely Sandra Bullock Before Speed made her the best-known bus driver since Ralph Kramden, Bullock was the token babe in Stallone's Demolition Man. Now she's calling the shots. Hot, hot, hot preview reactions to her newest film, While You Were Sleeping, opening April 21, have Hollywood aflutter. In the film, Bullock supposedly does for costar Bill Pullman what Nicole Kidman (in Malice) and Ryan (in Sleepless in Seattle) could not-make a leading man out of him. If Sleeping wakes up audiences, it could catapult the 28-year-old actress from the ranks of rising stars to the rarefied list of bankable women. Producer-director Irwin Winkler, currently putting Bullock through her paces in the thriller The Net, is confident that after Sleeping opens, ''Sandra will emerge as someone who can carry a picture. It's going to set the pace for her career as a leading lady.'' And that means her salary-now $2 million-will rise rapidly. An even bigger sign that Bullock has arrived: She's being wooed for the female lead in A Time to Kill, based on John Grisham's novel. That means she could join the elite group of actors who have starred in Grisham thrillers (which includes Roberts and Cruise). Like any fledgling on the verge, Bullock can't stop pinching herself. ''It took me a while to go, 'I'm here,''' she admits. ''Now I want to do something brilliant. I don't know yet. I haven't done it yet, but I'm going to do it.'' Maybe they all will.