Kim Kardashian, Lady Gaga, Kanye West, Demi Lovato & More Ring in the New Year!

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Happy New Year!

Celebs like Lady Gaga, Kim Kardashian and Kanye West and scads of other stars took over New Year's 2012 in style, partying from coast to coast at big bashes and intimate soirees.

So, how exactly did they bring in the New Year? We've got all the details!

MORE: Party Time: New Year's Eve With Kim Kardashian, Demi Lovato, Fergie & More!

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On the east coast, a Versace-cladLady Gagawas on hand at Dick Clark's New Year's Rockin' Eve in NYC's Times Square, performing in a Swarovski crystal-encrusted black cat suit with black platform shoes.

And never one to shy away from a quick wardrobe change, the pop superstar switched up her look, donning a silver Atelier Versace beaded gown with a silver crystal-covered headpiece to watch the ball drop at midnight.

Justin Bieber also spent New Year's Eve in NYC with girlfriend Selena Gomez at a private party at the Glass House in Manhattan following his performance at Dick Clark's Times Square shindig. At one point the "Baby" crooner was spotted picking Selena u! p and sp inning her around while they danced. So cute!

On the west coast, Kanye West and Fergie kicked off the New Year at the opening of 1 OAK in Las Vegas, where Kanye (who dubbed himself YEEZYWORLDPEACE for the evening) deejayed the party, spinning hits for partygoers for three hours!

Fergie, who hosted the affair, was spotted kissing hubby Josh Duhamel at midnight. And while she didn't perform, the Black Eyed Peas singer sang along to '80s music at her table, and was entertained by a magician who performed tricks for partygoers as well.

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Ed Graff

Joining Fergie and Kanye at the lavish affair were Joseph Gordon-Levitt, Kid Cudi, Topher Grace, Big Sean, Jason Ritter and David Katzenberg, among other celebs.

Meanwhile, John Legend performed at Moon Nightclub at Palms Casino resort in Sin City, and partied the night away with his fianc, model Chrissy Tiegen, whom he smooched at midnight.

Over at Tao in the Venetian Hotel, Kim Kardashian hosted a party in a white Gucc! i long s leeve mini dress, kicking off the night saying, "It's a tradition to ring in the New Year here at Tao!"

The E! reality starlet was spotted singing and dancing along to a Britney Spears song, and then her mom, Kris Jenner, who was also on hand, requested that the DJ play Kim's song, "Jam."

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As the clock struck 12, Kim told partygoers, "I am so excited and can't wait for 2012 to come. Countdown with me!"

Meanwhile, Samantha Ronsonspun at a party at Lavo in the Palazzo.

In Hollywood, Tom Cruise and Nicole Kidman's son, Connor Cruise, deejayed at the Big Bang New Year's Eve bash, where Lupe Fiasco, Cobra Starship and Rock Mafia performed.

MORE:Selena Gomez's New Year's Eve With Demi Lovato Still on Track

Outside of the States, Prince William and Kate Middleton spent New Year's Eve at a private party held in a tent in the back garden of the Duchess of Cambridge's family home in Berkshire, England, according to People.

Kate's sister, Pippa, hosted the affair, which was described as a "canvas palace" to the mag, and included more than 100 partygoers.

Prince Harry, who was absent from the party, brought in 2012 in Switzerland, at ski resort Verbier.

PHOTOS:Party Pics:Vegas