London got a large dose of star power today when the cast of The Hangover hit the red carpet to premiere the third installment of their franchise. Bradley Cooper, Justin Bartha, Ed Helms, Zach Galifianakis, Todd Phillips, Ken Jeong, and Heather Graham met up in front of the cameras to pose for pictures and chat among themselves, flashing plenty of smiles along the way. It was their second big event of the week after also bringing the movie to LA on Monday. It looked like Zach was on his best behavior in the UK following his funny antics at the West Coast premiere — Zach hopped into a car trunk before walking the carpet with his formerly homeless friend, Mimi Haist.

The promotions will continue for the gang in the run up to their film's Friday premiere. Make sure to check out our review of The Hangover Part III before you head to the theater this weekend!

Kate Middleton wore a canary yellow coat by Emilia Wickstead to Queen Elizabeth's annual garden party Wednesday. The pregnant duchess got to spend some quality time with her in-laws, Prince Charles and Camilla, Duchess of Cornwall, and smiled as she spoke with the guests. Each year, the queen hosts a tea party for 8,000 members of the British public. A reported 270,000 cups of tea are served, as well as thousands of sandwiches and slices of cake. Last year was the first time the Duchess of Cambridge attended the event, where Kate cut a much different figure in a lovely pink dress.

This year, Kate topped her springy coat with a Jane Corbett hat. As she waits for the arrival of her first child and heir to the British throne, the duchess has kept quite busy. Kate attended a friend's wedding over the past weekend, and has been shopping for baby supplies.

Nina Ricci-clad Carey Mulligan wielded an umbrella to premiere The Great Gatsby in rainy Sydney today. She had the help of costars Tobey Maguire and Joel Edgerton and director Baz Luhrmann to debut the film Down Under while Joel Madden, who is currently a judge on the Oz version of The Voice, was also in attendance. Last night wasn't the first time the Gatsby crew donned umbrellas as accessories since their Cannes premiere last week got rained on as well.

Mr. Gatsby himself, Leonardo DiCaprio, didn't make it to the latest press stop since he's still in Cannes unwinding. After wrapping his work duties, he let loose flirting in a Cannes nightclub over the weekend and later hit the water to take part in the yacht scene. Isla Fisher also missed out on the premiere in her native Australia since she debuted her other project Now You See Me in NYC last night.

Emma Stone and Andrew Garfield showed support for Emma's mom at the Peace, Love & A Cure Triple Negative Breast Cancer Foundation benefit in Cresskill, NJ, yesterday. The couple shared a sweet kiss before Emma took the stage alongside her brother, Spencer, to present an award to their mom, Krista, who is a breast cancer survivor. Emma also honored Alan Ennis, the CEO of Revlon, for the company's continued support of women with cancer. As an ambassador for the makeup brand, Emma has done her fair share of charity work with Revlon and even attended their annual EIF Run/Walk For Women in NYC earlier this month. But she wasn't the only star at yesterday's charity bash — Mary J. Blige dropped by the event, and she and Emma excitedly greeted each other during the cocktail reception.

Both Emma and Andrew are on the East Coast as they continue filming for The Amazing Spider-Man 2. Don't forget to support Emma and Andrew by voting in our POPSUGAR 100 bracket!

Kate Hudson, Chris Martin, and Tom Ford were among the stylish attendees at Gwyneth Paltrow's Goop Summer party held at Mark's Club in London yesterday. Gwyneth wore a printed silk dress by Prabal Gurung for the fashionable fete and posed for pictures with Kate, who was clad in a white A.L.C. jumpsuit and Smythe blazer. The two friends have each been staying busy, both personally and professionally — Gwyneth's weekly Goop newsletter is in its fourth year and has expanded to include designer collaborations and the recent launch of city guide apps. She also hit the red carpet for the Met Gala, celebrated big success with the blockbuster release of Iron Man 3, and gave us some laughs with her most over-the-top recent quotes. Kate, meanwhile, is diving into new projects after it was announced that she'll be joining the cast of Zach Braff's upcoming film, the Kickstarter-financed Wish I Was Here.

Both Gwyneth and Kate are in the running for the 2013 POPSUGAR 100 crown — and it's up to you to decide who will take it home. Head on over now to pick your favorite celebrity of the year, and you could be entered to win a gorgeous Victoria Beckham handbag!

Matt Damon joined up with his Behind the Candelabra costar Michael Douglas to premiere their new film at the Cannes Film Festival today. Matt also had his wife Luciana by his side and they snapped pictures of all the action as they made their way down the carpet. Matt and Michael are screening their HBO project in the South of France before it officially hits the small screen on Sunday, May 26. Earlier in the day, Matt and Michael attended a photo call and a press conference. They have been doing quite a bit of press for the biopic, which follows Liberace, played by Michael, and his young lover, played by Matt. Naturally, a story about a couple had to involve love scenes, and Michael revealed in a recent interview he wasn't exactly put off by the idea of kissing one of America's best-looking actors. He said, "As far as making out with Matt, it’s not so bad. We rehearsed the scenes. For me, I guess the biggest thrill is, when I first saw it, after a few minutes, I really forget it’s Matt. Matt and Mike, you know? I just forget it’s us."

Matt is in Cannes after wrapping up filming for his upcoming film with George Clooney, The Monuments Men, in Germany. The pair celebrated finishing the film by having a boys weekend at George's Lake Como estate earlier this month.