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Lady Gaga celebrated after her sold-out Radio City Music Hall concert with one of fashion’s favorites—Marc Jacobs! The designer accompanied the singer to 1Oak in N.Y.C.’s meatpacking district where bottles of champagne were popped and sprayed, drenching the crowd, including Jacobs! Gaga danced to ’80s tunes and a few of her own hits in a black minidress (heavy on the mini) and shades resembling Mickey Mouse ears. More

Alexa Chung, Anne Hathaway and Hilary Swank were among the stars that flocked to the City of Lights to see the Spring 2010 Haute Couture collections this week. Swank turned heads at the Ritz in a blue one-shoulder Elie Saab where she attended Etam’s presentation of their Natalia Vodianova collection. Over at Chanel, Chung showed her head-to-toe support in the label’s cream dress and clogs. Hathaway lit up the front row at Armani Prive where she eyed “about seven” looks from the collection. “I have a few events in mind,” she told reporters. “If Mr. Armani would be generous enough, I’d love to wear them.”

Anime-inspired brand Tokidoki partnered with the American Red Cross to design a T-shirt for Josh Duhamel’s Youth Run for Haiti event. Participants in Saturday’s 2-mile run along the beaches of Santa Monica included Duhamel, Glee‘s Dianna Agron and Molly Sims (not pictured), all of whom sported the adorable red tee. The shirt is now on sale for $25 at Tokidoki’s Los Angeles store and on their Web site, with all proceeds going directly to the Red Cross relief efforts in Haiti.

Scarlett Johansson made her Broadway debut Sunday night in Arthur Miller’s A View From the Bridge and, according to The New York Times, she melted “into her character so thoroughly that her nimbus of celebrity” disappeared. An InStyle editor on hand reported back that “she wears the period fashions beautifully in the show and holds her own with seasoned theater vets” like Liev Schreiber. “The audience let out a cheer when she entered for her curtain call,” he added. More

In addition to scoring must-haves at gifting suites and making the rounds of movie screenings, celebrities at Sundance are giving back to some worthy causes. At the Lia Sophia lounge at The Lift festival stars America Ferrera and Kristen Stewart stopped to sign a Muscle Milk refrigerator to be auctioned off to raise funds for A World Fit For Kids!, an after-school mentoring program for underprivileged youth. Kristen Bell and Kerry Washington signed a surf board at The Village at the Yard’s FilterForGood booth that will benefit the Surfrider Foundation’s efforts to clean up the world’s oceans and beaches. More

Dressed in jodhpurs and a derby hat, John Galliano rode off with our hearts with his breathtaking, equestrian-themed creations for Christian Dior’s spring haute couture show in Paris. Tailored riding jackets, romantic lace confections and billowing silk ballgowns referenced both the Belle Epoque era of British couturier Charles James and Dior’s iconic 1947 New Look fashion show. Dita Von Teese tweeted from the front row that the show was “a marvel.” Fellow front-rower Kylie Minogue agreed. “What John did today was take it to another, more extravagant and beautiful level,” she told Fashion Wire Daily.

Brad Pitt, Robert Pattinson and Jon Hamm have three of the most chiseled and most photographed faces in Hollywood—but lately, they’ve been shrouded in heavy facial hair! But no, the stars aren’t using their beards to dodge the paparazzi. Pattinson’s look, which debuted at Friday night’s Hope for Haiti Now telethon, is reportedly for his role in the upcoming film Bel Ami with Uma Thurman. Pitt’s lengthy goatee is also in preparation for the movie The Lost City of Z, in which he plays a British colonel exploring the Amazon. More