The Best & Worst Dressed Celebrities of 2010

From Blake Lively and Rihanna's show-stopping ensembles to Christina Aguilera and Kim Kardashian's style slip-ups, it's been an eventful year for fashion. See pictures of the best and worst dressed stars of 2010.

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Best Dressed: Blake Lively

Blake Lively occupies a rare niche in the fashion world: She's a star on Gossip Girl by day and on the arm of Karl Lagerfeld by night. Her rise to fashion prominence this year is due in large part to an inspired sense of personal style that it at once disheveled, often unexpected, and always fashion-forward. Lively, who famously does not employ a stylist, works directly with designers to procure their best dresses. Such was the case when she wore the first look from the Lanvin Spring/Summer 2011 runway at the Spike TV Scream Awards in Los Angeles in October. And, of course, her love affair with Anna Wintour doesn't hurt: Lively has graced multiple Vogue covers already, including the cover of its special Best Dressed issue in November.

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Best Dressed: Kate Middleton

The world has been waiting for Kate Middleton to make a sartorial slip-up, but so far, the princess-to-be has been spot-on. Her style is classic without being frumpy; sexy without showing too much skin, flamboyantly British (see her many hats) and refreshingly simple. To attend a friend's country wedding in October, Middleton wore a silk blue dress, black fitted blazer, and dramatic lace hat. To announce her engagement to Prince William in November, she matched her new sapphire ring with a royal blue wrap dress by Issa. Within 24 hours, the design sold out from Harvey Nichols, as did bargain replicas of the dress. And now the race is on to see what Middleton will wear at the "wedding of the century," with designers from Karl Lagerfeld to Christian Lacroix submitting sketches to WWD for their dream Middleton wedding dress. As Gucci's Frida Giannini said of her design, "I admire the balance Kate Middleton strikes between elegant and contemporary with her unmistakable style. For her, I had in mind clean lines, soft shapes, and classic touches such as the boat neckline and distinctive train."

Evan Agostini / AP Photo

Best Dressed: Elle Fanning

Twelve-year-old Elle Fanning came to our best dressed list relatively late in the game, proving herself a style star in the final weeks of the year as she made the rounds promoting her new film, Somewhere. But in a span of a few weeks, she proved that she's a fashion heavyweight: She wore a tan suede and gold leather embossed dress from Rodarte's Spring runway at the film's New York premiere. According to Refinery29.com, Fanning "has immediately put herself on Vanity Fair's ‘Best-Dressed List' radar."

Laurent Cipriani / AP Photo

Best Dressed: Anna Dello Russo

If Kate Bosworth ushered in simplicity this year, Anna Dello Russo gave us everything but. This year, the editor at large of Nippon Vogue made street style a parade of colorful surprises. To the "Eyes Wide Shut"-themed 90th Anniversary of French Vogue, Dello Russo took the prize in a white custom Pucci dress and a Gareth Pugh headpiece from his Spring collection. As she blogged in preparation for the event, "Leave the couture to Carine [Roitfeld], she will be the QUEEN of the party." But unfortunately for her French counterpart, Dello Russo effectively stole the show. All hail, fashion's new Anna!

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Best Dressed: Carey Mulligan

Carey Mulligan's dimples and pixie haircut only get her so far: The rest of her look is thanks to impeccable style, marked by a series of mature dresses with young flair. She's a throwback star, equally likely to be seen gracing the streets in an oversized men's shirt, a pair of penny loafers, and Ray-Ban sunglasses. Mulligan's red carpet highlights include the Azzaro Fall 2010 dress she wore in Cannes for the premiere of Wall Street: Money Never Sleeps in May, and the Chanel sequined dress at the CFDA/Vogue Fashion Fund Awards in November.

Rabbani and Solimene Photography, WireImage / Getty Images

Best Dressed: Kate Bosworth

Kate Bosworth has it easy: a petite frame, a symmetrical face, and relationships with several important designers. This year, Bosworth managed to stun in dresses that didn't, in themselves, pack a whole lot of punch—which speaks volumes to her ability to accessorize in the right way. She landed in the front row of Calvin Klein's spring show during New York Fashion Week in a crisp blouse and brown leather skirt by the designer that was just right, opted for a nude off-the-shoulder dress (which she paired with red pumps and red lips) also by Klein later this year, and stopped the show at Chateau Marmont in July in an all-red Vanessa Bruno ensemble.

Matt Sayles / AP Photo

Best Dressed: Dree Hemingway

Off the runway, most models throw on a white T-shirt and a pair of combat boots, and they're lauded for "Off-Duty Model" style. But Dree Hemingway, the 23-year-old great-granddaughter of Ernest, gets points for actually getting dressed. And it's more than that: Hemingway has a minimalist cool about her but isn't afraid of a little color, as she proved in a neon Valentino Spring 2010 Couture dress at the amFAR gala in Cannes this summer. But she's also a fan of subtlety, which she channeled in a two-toned Calvin Klein Collection dress at the Met's Costume Institute Gala in May. As WhoWhatWear.com wrote of Hemingway: "Her wardrobe preferences tend to be quite Parisian in nature—with a dash of California casual thrown in for good measure."

Samir Hussein / Getty Images for International Herald Tribune

Best Dressed: Victoria Beckham

Victoria Beckham has always been chic, but this year she pulled away from the pack. The Spice Girl-turned-designer was nominated for best designer brand at the British Fashion Awards alongside labels such as Burberry and Pringle. This year, Beckham's Fall/Winter collection was inspired by Dick Tracy; and with spring, she celebrated the return of the waist. Beckham herself turned up in a series of her own bell-shaped minidresses in bright pinks and yellows, and, in one particularly well-coordinated outfit, designed herself a pair of pink gold 6-inch platforms to match her rose gold Rolex. She said of her Fall collection: "I feel the clothes express how my own personal style has evolved, more relaxed, a little more slouchy, but still structured."

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Best Dressed: Daphne Guinness

Daphne Guinness has long been a collector of couture, a close friend to the most prominent designers, and a general beacon of style. But when Alexander McQueen tragically committed suicide last February, Guinness inherited his mantle, and spent the remainder of the year honoring him through her wardrobe. She walked the runway in a gold jumpsuit by the designer for a tribute during Naomi Campbell's Fashion Relief for Haiti Show in February, and donned a dramatic black ensemble by the designer to his memorial service at London's St. Paul's Cathedral in September. Recently, Guinness wore an otherworldly diaphanous Givenchy dress to a W Magazine party at Art Basel in Miami.

Peter Macdiarmid / AP Photo

Best Dressed: Carla Bruni

French First Lady Carla Bruni is the last bastion of Old World style, paying daily tribute to Jackie O. with her strands of pearls, pillbox hats, and kitten heels. Bruni is practically a one-woman ambassador for Christian Dior, as she has stunned this year in many of the house's designs. The Telegraph's fashion director Hilary Alexander called Bruni "French fashion's secret weapon," as she is simultaneously "as diplomatically correct and on-trend as it is possible to be." But this year, Bruni also surprised us in casual fare on the Paris set of Woody Allen's Midnight in Paris, where she looked equally as glamorous in jeans and a linen shirt.

Official White House Photo by Pete Souza

Best Dressed: Michelle Obama

Michelle Obama's place on the best dressed list may seem like a given—after all, whenever she leaves the White House in something, even if it's just down to the pumpkin patch, the press analyzes her every outfit. (She’s seen here wearing a green Barbara Tfank dress.) The Harvard Business Review valued MObama style as a $2.7 billion industry. As The Daily Beast's Kate Betts put it: "She has taken a page from first ladies like Laura Bush, Hillary Clinton and Jackie Kennedy. But it might just be the Jackie-ness that proves to be Michelle's most effective political tool. She uses her style to get our attention, and then she delivers her message."

Dave M. Benett / Getty Images

Best Dressed: January Jones

Betty Draper would be proud: when she's not in bell skirts and pearls, January Jones packs some serious punch. She was a favorite at the 2010 Golden Globes in an asymmetrical black Lanvin gown, which she paired with a wristful of Neil Lane diamonds and a satin headband. Otherwise, she's been a Versace loyalist (she recently posed nude for the brand's Spring/Summer accessories campaign) wearing a show-stopping strapless blue Atelier Versace gown with a dramatic train to the Emmy Awards, and, a revealing black Versace cocktail dress from the Spring 2011 collection to Donatella Versace's dinner for Central Saint Martins in London this fall.

Laurent Cipriani / AP Photo

Best Dressed: Natalia Vodianova

This year, veteran model Natalia Vodianova walked the runway for seemingly everyone from Alexander Wang to Diane von Furstenberg to Roberto Cavalli. But off the catwalk, she maintained a strong sense of personal style. She supported up-and-coming British designer David Koma, wearing one of his designs in London in September, looked regal in a floor-length Balmain gold sequin number this fall; and wore a sexy black lace dress at French Vogue's 90th Anniversary "Eyes Wide Shut" party in November.

Pascal Le Segretain / Getty Images

Best Dressed: Rihanna

This year, Rihanna's style was so polarizing that numerous style blogs named her one of the the worst-dressed celebrities of 2010. But that risk-taking is exactly why we love her. Whether it was the sculptural Viktor & Rolf dress she wore at the pre-Grammys party in January or the red lace Stella McCartney dress at the American Music Awards, Rihanna boldly went where few more fashion-conscious stars have gone before, but played it straighter than other kooky lady-musicians like Lady Gaga, Ke$ha, and Katy Perry.

Jemal Countess, WireImage / Getty Images

Best Dressed: Helen Mirren

Thanks to nude photos in New York magazine, there's one thing we learned about Helen Mirren this year: She's got curves. And she played them up, in everything from a figure-hugging navy Badgley Mischka dress to the Tony Awards in June to a cinched silver dress to the premiere of Love Ranch later that month.

Jordan Strauss, WireImage / Getty Images

Worst Dressed: Kristen Stewart

Perhaps it's Kristen Stewart's obvious resentment of fashion that lands her on our Worst Dressed list this year. She seemed to be going through the motions at several events this year, wearing a beautiful navy Monique Lhuillier at the Oscars in March and a stunning beaded Chanel dress to the BAFTAs—all without a single piece of jewelry. (As GoFugYourself wrote of her BAFTAs ensemble: "K Stew looks like she ran a half-marathon on Thursday and hasn't showered since.") Even the Chanel Spring 2008 Chanel Couture dress she wore to the Costume Institute Gala was a bit of a fright. At a panel to promote Welcome to the Rileys at the Los Angeles Film Festival in June, Stewart arrived in a black dress and heels, but swapped them for beat-up Converse sneakers to answer questions. We're all for comfort, but sneakers really don't match black mesh.

Jean Baptiste Lacroix, WireImage / Getty Images

Worst Dressed: Lindsay Lohan

Lindsay Lohan spent a good part of 2010 in an orange jumpsuit—but her other ensembles were really just as bad. Over her multiple appearances in court, Lohan gave us loose gray pants, a boxy 6126 blazer, and even jeans and a T-shirt.

Dave Fisher / AP Photo

Worst Dressed: Eva Longoria

Eva Longoria always makes an effort to look glamorous—but usually ends up looking like she's heading to prom instead. This year, she gave us a precious Marchesa fringe dress, which one bargain shopping site showed fans how to copy with a discounted "Celebrity Inspired Fringe Party Dress." And at the MTV Europe Music Awards in Madrid in early November, Longoria left her pants at home, wearing a structured black George Hobeika dress that seemed more like a blouse.

Evan Agostini / AP Photo

Worst Dressed: Uma Thurman

It's been a hard year for Uma Thurman. First, a psychiatric patient was jailed for stalking her. Then, her film Motherhood earned only £88 ($136) during its U.K. opening weekend. And somehow, as she saw hurdles in her professional life—her wardrobe followed suit. She shocked us in a series of misguided outfit choices this year, from a see-through Valentino dress at London's Fashion Rocks event last December to a shapeless pairing of a black tutu dress and a tan waffle coat Quentin Tarantino's Friar Club Roast. And as if it wasn't bad enough, it turned out that the offending coat is a Thurman favorite. As one blogger at Oh No They Didn't points out it's "the same winter coat we've seen for years," making appearances as early as 2005.

Dan Steinberg / AP Photo

Worst Dressed: Christina Aguilera

It'd be one thing if Christina Aguilera's outfits in Burlesque—boas, fishnets, bandage dresses, fringe—were a serious departure from her everyday fare. But somehow, Aguilera's personal wardrobe in 2010 consisted of boas, fishnets, bandage dresses, and fringe.

Frazer Harrison / Getty Images

Worst Dressed: The Kardashians

Although their DASH clothing stores are a national hit and the K-Dash by Kardashian line sold like hotcakes on QVC, it's hard to remember that Kardashians really are terribly dressed. From one bandage dress and thigh-high boot after another, Kim, Kourtney, and Khloe (and even half-sisters Kendall and Kylie Jenner are guilty, too) lowered the style bar this year. And it's good to know that the sisters' style is influencing young girls everywhere: 17-year-old Disney star Demi Lovato told People magazine that she loves Kim Kardashian's style because "She wears clothes that fit her body…I've been embracing my body as I've been getting older, I'm starting to have curves and I'm embracing it and kind of looking to her style to help me out with that."