Stars at Fashion Week: London, Milan, and Paris

Longtime Marc Jacobs fan Sarah Jessica Parker shared a big hug with the Louis Vuitton designer backstage after the French brand's presentation in Paris.

Alicia Keys and Rosario Dawson arrived at Kanye West's ready-to-wear presentation in Paris to support the rapper's fashion ambitions. Before the night was through, Keys Tweeted a picture of the Paris with the simple caption, "Bonsoir!"

A fur-clad Kim Kardashian stepped backstage after Kanye West's fashion show to congratulate the singer on his latest collection. "So excited to see my friends in Paris!" the reality star Tweeted.

Pop singer Katy Perry and actress Rosario Dawson caught up at the Yves Saint Laurent fashion show during Paris Fashion Week.

Salma Hayek and her husband, fashion businessman Francois-Henri Pinault, caught the Yves Saint Laurent fashion show from the front row.

Katy Perry complemented her blue hair with a pink chiffon dress at the Miu Miu fashion show in Paris.

Actress Eva Green joined Tim Burton and Helena Bonham Carter at a private dinner celebrating a new exhibition honoring Burton at the famous Parisian movie museum, La Cinematheque.

Katy Perry posed with a fan's pint-sized pup, Gucci, outside her hotel while in Paris for fashion week. We wonder what her own furry friend, Kitty Purry, has to say about this!

Hayek and Keys wore coordinating black and white looks to the Stella McCartney show in Paris.

The actress posed with Dior designer Bill Gaytten at the label's Paris Fashion Week show.

Alba and her sister-in-law Nikki sat front row at Lanvin's Paris show with the label's CEO Thierry Andretta.

Swinton posed with Lanvin designer Elbaz at the label's Paris Fashion Week after-party.

The face of Miss Dior Handbags was pretty in pink lace and a white overcoat at the Christian Dior fashion show in Paris.

Salma Hayek took a front row seat at the first-ever fashion show for Alexander McQueen's diffusion line, McQ.

Heiress Olivia Palermo posed in a printed dress before heading inside to see the Christian Dior's fall collection.

Katy Perry was spotted out and about during Paris Fashion Week in head-to-toe Vera Wang. Enjoying the City of Lights, the "Part of Me" singer Tweeted, "Toasted ham and cheese on a baguette in the morning #parisisperfect"

The Twilight Saga

star Kristen Stewart popped up in the front row at Balenciaga rocking fierce leather pants tucked into sandals by the brand.

Actress Salma Hayek posed in a maroon mini and sky-high platforms before finding her front-row seat at Balenciaga.

French actress Clemence Poesy was spotted outside of the Balenciaga show in Paris in brown leather jacket layered over a tangerine tee.

Dame Helen Mirren joined Italian actress Monica Belucci in the front row at Dolce & Gabbana's fashion show at the Metropol in Milan.

After walking the Roberto Cavalli runway, Campell attended a private dinner for the designer at the Just Cavalli Cafe in Milan.

Burberry model Huntington-Whiteley and actress Bosworth stood side-by-side at the Burberry fashion show. "Here's looking at you Christopher Bailey! Just. Gorgeous," Bosworth Tweeted to Burberry creative director Christopher Bailey after the show.

"The @burberry fashion show in london was amazing," Tweeted the Black Eyed Pea after the watching the Burberry show alongside British It-girl Alexa Chung.

Clemence Poesy (with the label's signature trench on her lap) took in Burberry's latest collection from the front row with actor and Burberry model Eddie Redmayne.

Stella McCartney welcomed Rihanna (in a McCartney design) to help her celebrate her fall collection presentation in London.

The top model (in Stella McCartney) and husband Jamie Hince were on hand to toast to Stella McCartney's new collection.

Actress Elizabeth Olsen and Lana Del Rey went backstage to congratulate Mulberry designer Emma Hill after the label's fashion show. The singer carried her new white "Del Rey" bag by Mulberry, which Hill designed with her in mind.

Best Actress nominee Michelle Williams took a break from her press tour for My Week With Marilyn to enjoy the Mulberry fashion show in London.

Olivia Palermo sat front row at many shows during London Fashion Week, including Mulberry, shown here.