For five years, we've followed the golden girl. Sienna Miller smiles from magazine covers. She dominates the red carpets. She's a regular on TMZ. And she's suffered, so prettily, the burden of her fame: The humiliating breakups laid bare in the press. The blow-back from careless interviews. The 'homewrecker' catcalls in the blogosphere. The shame of topless photos, caught on vacation, now all over the tabs; all the horrible invasions of privacy. Right about now you're thinking: 'Who's Sienna Miller again? Remind me why I'm supposed to know her?' It's OK! There's absolutely no reason you should know who she is, not even if you're a religious follower of the celebrity press that tracks her so closely. She's an actress, but odds are you've never seen a single one of her movies or TV shows. Miller is a pioneer in a new kind of fame that is changing our celebrity culture, a fame that is increasingly disconnected from the star's success in the field for which he or she is ostensibly famous. Sienna Miller is not famous. She is (ital) famesque.(end ital) Famesque is not the paradox of the unlovable A-lister -- the Nicole Kidman types who win all the awards but lose the hearts of the multiplex. It's not the quandary of the shrinking star (Ricky Martin), gossip-bait still on the strength of a few decade-old monster hits. The famesque are distinct from their has-been cousins who extended their run via reality shows and basic-cable hosting gigs (Bill Rancic, Mario Lopez) and from the train wrecks (Lindsey Lohan) whose detour from genuine fame is compelling because they had it and blew it. The famesque of 2009 are descended from that dawn-of-TV creation, the Famous for Being Famous. Turn on a talk show or 'Hollywood Squares' and there'd be Zsa Zsa Gabor, Dr. Joyce Brothers, Charles Nelson Reilly, so friendly and familiar and -- what was it they did again? But the FFBF always seemed to know how marginal they were -- that was their charm. And they never, ever made the cover of People. The truly famesque possess the seeming gravitas that comes with a title and the suggestion of a job -- actor, singer, pro athlete. It's just that ... you've never seen them act, or heard them sing, or watched them play. Instead: You read about them. A lot. There was a time when the growth of our worldwide round-the-clock entertainment-news industry was gravely threatened by the fact that there weren't enough legitimate celebrities to power it -- until the famesque stepped in to fill that market niche. They single-handedly saved TMZ's business model. Because, hey, it's not every day Mel Gibson gets drunk and insults a cop. So: Sienna Miller, the most famous obscure art-house film star in history. The celebrity press often drops the name of a star's most recent or biggest project to remind you who they are. For Miller, it's 'Factory Girl' (2006), in which she starred as drug-damaged '60s scenester Edie Sedgwick. You didn't see it, right? It made only $1.6 million in U.S. theaters. Miller's biggest-grossing movie was the fantasy-adventure 'Stardust,' in which she was billed about sixth or seventh behind Michelle Pfeiffer and Robert De Niro. Not that you saw that one either: It made only $39 million, not a lot for that kind of thing. Then how'd she become so famesque? Us Weekly News Director Lara Cohen, who says she's been with the magazine 'since the era of Bennifer One,' says it started with being incredibly photogenic. Maybe five years ago, Miller had one big hit film in the U.K. ('Layer Cake,' which never took off here) and a lot of buzz. 'A lot of the photo agencies we work with are based in London,' Cohen said. 'So we were seeing a lot of photos of her. But she was interesting as a style icon in a way that Jordan or some of the other British celebrities were not.' (We don't know who Jordan is either.) Miller gained momentum, Cohen says, with her knack for 'no-holds-barred, watch-your-mouth interviews.' As during the filming of 'The Mysteries of Pittsburgh,' when Miller, interviewed by Rolling Stone, slammed her host city as '(rhymes-with-Pitts)burgh.' Says Cohen, 'It was the most publicity that movie got.' (It grossed less than $100,000.) And Miller harnessed the power of celebrity dating, where 'one plus one equals four,' Cohen says. Take Posh Spice, whose union with soccer star David Beckham catapulted her to heights poor Sporty and Scary could never climb. Miller became famesque by dating Jude Law, then really famesque when he cheated on her with the nanny -- to the point that she was the one who made Balthazar Getty famesque (even though he's the one with the hit TV series, 'Brothers & Sisters') when he reportedly ran off from his wife with her for a while. But Miller's groundbreaking famesque is threatened. She stars in 'G.I. Joe: The Rise of the Cobra,' a big dumb movie that opened Friday on 4,007 screens. By now it's possible that 10 million Americans just saw Sienna Miller on the big screen. What happens then? Will we lose interest? Will she stop saying provocative things? Stop dating messed-up dudes? (Cohen's not worried: 'She has a really great publicist. One of the best in the business.') Who else is famesque? Set aside that one hit album from a decade ago, and Jessica Simpson pretty much defines it. She's a 'singer,' but do you know or remember her songs? Likewise her movie roles, most in films that tanked. That cultural-touchstone reality show with husband Nick Lachey? Brief, and canceled four years ago, like their marriage. But there she is on the cover of Vanity Fair, no less, standard-bearer for all those blond stars (Kate Bosworth, Denise Richards) whose love lives are their true art form. Or 'NFL star' Matt Leinart, who, like Anna Kournikova, has done better on the 'hottest singles' and 'most beautiful' lists than the playing fields. He may never be the starting quarterback again, but he still draws the paparazzi. The famesque are young, beautiful, and noticeably white -- a formula that seems to disproportionately draw the paparazzi and dominate the gossip magazines. One could argue that African American starlet Kerry Washington (so gorgeous! So ubiquitous! What was she in again?) should be more famesque than she is. One last example, someone who may yet top Sienna Miller in the art of famesque. Ashton Kutcher. 'But Ashton Kutcher is famous!' you say. 'He's a big star!' Star of what ? Of the TV commercials, where he plays himself? Of the red carpets, where he clowns and mugs with his beautiful older wife? Of a million great interviews, where with expert calibrations of wit and self-deprecation he divulges how crazy and blessed his life is? Name one of his movies. Just one. And no, not 'Dude, Where's My Car?,' another one. See? Famesque. 