It made sense that Ms. Mara, blandly pretty in her Social Network days, would hitch her rising star to her character’s signature look. Trish Summerville, the Dragon costume designer, had already capitalized on the best-seller heroine’s appeal with a capsule collection at also-Swedish H&M.

But who would have guessed that when Ms. Mara showed up for the Oscars last month in a lacy cream Givenchy gown, Lisbeth’s weird baby bangs—short, black and severely straight across her forehead—would stay in the picture?

The look was created for the film by Danilo Dixon (Gwen Stefani’s hairstylist), with the logic that Lisbeth would need her hair out of her eyes during those all-night hacking binges. Kind of like the DIY crop Angelina Jolie wore as Acid Burn in Hackers, but with a minimalist precision suited to a chick who has probably hacked Ikea.

Since then, bangs have shortened on stars as diverse Zoe Kravitz, Krysten Ritter and indie music It girl Grimes. High-fashion magistrates have given baby bangs their seal of approval in back-to-back seasons.

In October, John Galliano juxtaposed fresh-cropped baby bangs with sheer boudoir gowns adorned with ruffles, ribbons and beads. The effect: Barbiturate-addled silent film star locks self in bathroom with scissors.

In February, Versace models walked in kinky mesh boots, fitted leather dresses embroidered with Christian iconography, and uniformly baby-length bangs. (There are reports of clip-ons.) Were the fringe a half-inch longer, it would have been your standard Opus Dei bondage thing. As it was, the stunted bangs gave the models alien ovoid foreheads and the look evoked a conspiracy of femme cyborgs in the Vatican.

Generally, bangs are too functional to be trendy. Zooey Deschanel’s brow-grazing Françoise Hardy bangs are part and parcel of her She & Him ’60s songstress act. When Nicole Kidman wears bangs, celebrity blogs wonder if she’s trying to conceive. (Botox is discouraged during pregnancy.) For others (Olivia Wilde, Rose Byrne) bangs may simply be the fastest way for a starlet to differentiate herself from the herd of identically proportioned brunettes.

But baby bangs are different. For one, they flatter no face shape. On the contrary, they can make even the most golden ratio-adherent beauty look a little off. We might have mistaken Ms. Ritter for Penelope Cruz’s other sister until she adopted the baby bang. She was prettier then, but now we can’t stop looking at her.

“Short bangs can be flattering if it is professionally done and the person really owns it,” Jennipher van Bogart, a stylist at Woodley and Bunny in Williamsburg told The Observer, adding that the girls coming off the L have been asking for short bangs more frequently since January, many citing Michelle Williams. Women with square-shaped faces especially should seek professional guidance, she cautioned.

“It’s a major commitment,” agreed celebrity stylist Sally Hershberger. “That is going to be your look, you know? It’s like a piece of art.”

Despite having hit the runway, baby bangs remain a DIY hallmark. Laia Garcia, a 20-something stylist and fashion writer, accidentally got the look back in September when she overdid it on a home trim. “But once I remembered the late ’90s Raf Simons portraits of dudes with asymmetrical haircuts, I decided to embrace them,” she explained.

Ms. Garcia said she pulls out the scissors every two weeks or so. Her bangs usually end up crooked, which she also embraces. Failing that, she side-combs. Around Fashion Week, she said, she shortened them even more, to a length she called “fetus bangs.”

“Looking at the pictures where I am sporting them, I can see that I went over the line,” she said.

But according to Calvin Klein, she hit the mark. That week, creative director Francisco Costa sent Patricia van der Vliet and Tatiana Krasikova down the runway with full fetal fringe. Ms. Mara sat in the front row.

The baby bang is not to be confused with the curled and bowed bangs Beyoncé Knowles wore in videos for “Video Phone” and “Telephone.” Those were Bettie bangs, an homage to ’50s dominatrix pin-up Bettie Page. Or were they a reference to Page’s ’90s Third Wave revivalists (Uma Thurman in Pulp Fiction; Janeane Garofalo in Reality Bites)? Or, worse, the fetish-y hybrid sported by Katy Perry?

No, unlike last year’s “Bettie” bang, the baby bang ends before the middle point of the forehead, Louise Brooks length or shorter. While Bettie bangs lend the wearer a touch of childlike surprise, alarm is often in the eye of the beholder of baby bangs. When coupled with a little eyebrow modification—the lines penciled on Mariacarla Boscono in Yves St Laurent’s spring print campaign or Die Antwoord rapper Yolandi Visser’s bleached brows, for example—it’s downright freakish.

This is the critical distinction between Bettie and baby bangs. Page’s dominatrix pics seem to subvert pin-up objectification, but she was still posing for the pleasure o f a male audience. Salander’s bangs were defiantly unattractive, like a dare not to fall in love with her long neck and high cheekbones.

Could baby bangs be a move to overthrow the male gaze? Is this what an apathetic generation’s political haircut looks like? Is ugliness the only remaining expression of sexual empowerment?

Leandra Medine, whose fashion blog The Man Repeller specializes in such topics, likened the baby bang to “a cross between Isabella Blow—who stands for most everything I do—and Jim Carrey’s Dumb and Dumber character. A shroom groom, if you will.”

So that’s a yes?

The look betokened “a crucial-to-mankind personality,” she said, “but most certainly not the person you intend to take home at night’s end.”

Like Ms. Hershberger said, big commitment, these bangs. Depending on your audience, you could be projecting associations as disparate as “melancholy milliner” and “mentally handicapped chauffeur.”

"To have baby bangs is to enter a weird world of associations that you just gotta be able to run with," Ms. Garcia explained. "Although I did make sure to tell everyone who commented on my bangs that they were Raf Simons bangs and not Girl with the Dragon Tattoo bangs.

But all of the baby bang associations seem to coexist harmoniously in Montreal electro-pop artist Grimes, a.k.a. Claire Boucher.

The 23-year-old’s music is often described as “post-Internet” because her influences are so apparently random (she has named Nine Inch Nails, Outkast and Christina Aguilera, for instance).

Her personal style might be called post-Internet too. She resents being cute, and her style icons include Marilyn Manson, the graphic novel Tank Girl, Leeloo from The Fifth Element and Princess Zelda.

It probably goes without saying that she cuts her bangs herself.

Ms. Boucher said the look’s reception varies geographically. “Like, people in Miami will try to have sex with you, people in Mexico want hugs,” she explained. “Phoenix was like 60 percent bros and I got tons of love letters and there was a fight. San Francisco was like 80 percent girls and all the guys were gay and everybody was dancing.”

That said, her baby bangs have evolved over time. She wore a black Mia Wallace bob in her self-directed video, “Vanessa.” In a follow-up, “Crystal Ball,” the bangs were cropped to Lisbeth length with the sideburns shaved, a kind of modified Chelsea. On the cover of April’s Dazed and Confused (shot by Hedi Slimane), they’re shorter still and natural brown—so as not to distract from her massive Givenchy septum ring.

“Everything I do is about empowering myself,” she explained. “Not as a female or anything, but just in general. I’m realizing that the way one is marketed is directed primarily by visual presentation.”

But if one were marketing the baby bang, it’s never looked better than in the video for “Oblivion,” the single off her latest album, Visions. Trimmed halfway between a Bettie bang and the YSL microbang and dyed bubblegum pink, the cut completes a look that involves a baggy sweatshirt, a tulle skirt and combat boots. Grimes interpretative-dances her way through a football stadium, singing about finding someone to hold her hand in a breathy, lispy falsetto.

“I love putting together an image that I think is really beautiful, feminine, even sexual,” she said, “but it’s also very important to me that I don’t feel exploited and that I feel tough.

“So I dunno, yeah,” she added, “it’s a fine balance.”

kstoeffel@observer.com