Celebrity New Year's Eve Party Stars From N.Y.C. to Sin City, see how Gaga, Fergie, Rihanna and more popped the cork on 2012 By People Staff Published on January 1, 2012 11:00 AM Share Tweet Pin Email Trending Videos 01 of 18 HAVING A BALL Jason Kempin/Getty Looks like Lady Gaga found someone – or something – to kiss! Following her New Year's Rockin' Eve performance in N.Y.C.'s Times Square, the singer plants a smooch on a sphere before launching the official ball drop with Mayor Michael Bloomberg (not pictured). 02 of 18 SHOW-TOPPER John Sciulli/WireImage Who can resist a hunk in a hat? Certainly not Fergie, who preps her pucker for hubby Josh Duhamel at the grand opening of The Mirage's 1 OAK Las Vegas, where she served as host and also performed at the New Year's Eve event. 03 of 18 HEY MR. DJ! John Sciulli/WireImage Also at the 1 OAK Las Vegas blowout: Kanye West, who got the party started by spinning tunes under the pseudonym YeezyWorldPeace. 04 of 18 SHEER DELIGHT Gustavo Caballero/Getty Days after making a casual McDonald's run in London, Rihanna glams it up for the Sean "Diddy" Combs-hosted CIROC: The New Year 2012 bash in Miami. 05 of 18 TIMES PAIR Mike Coppola/Getty Pitbull and Justin Bieber buddy up in N.Y.C.'s Times Square, where each appeared on New Year's Rockin' Eve. Pitbull performed his hits "I Know You Want Me" and "Give Me Everything," while the Bieb rang in the new year with something old: the Beatles classic "Let It Be." 06 of 18 RAISE YOUR GLASS Denise Truscello/WireImage Joined by Dancing with the Stars pro Mark Ballas and her mom Kris Jenner at Las Vegas's TAO Nightclub at the Venetian, soon-to-be divorcée Kim Kardashian leaves behind a tumultuous 2011 and toasts to being in 2012. 07 of 18 COZY COUPLE Bobby Bank/WireImage Vowing to and enjoy life following her recent double mastectomy, Giuliana Rancic cuddles up with husband Bill at the NIVEA Kiss Stage in New York's Times Square. 08 of 18 FORGET 2011! Michael Loccisano/Getty Also at the NIVEA Kiss Stage in N.Y.C., Cee Lo Green wows the crowd with his take on John Lennon's "Imagine" for NBC's New Year's Eve with Carson Daly special. 09 of 18 OUT OF THIS WORLD Kevin Winter/Getty In Los Angeles, a very Jetsons-esque Nicki Minaj looks ready for the future – which will likely include an appearance at the Feb. 12 Grammys – while performing "Super Bass" on Dick Clark's New Year's Rockin' Eve. 10 of 18 BOWLED OVER Astrid Stawiarz/Getty Check out that footwork! Dancing with the Stars pro Karina Smirnoff has a heel of a time bowling with a bottle at Joonbug's End of the Year Bash in N.Y.C. 11 of 18 SPARKLE & SHINE Michael Tran/WireImage Designer Lauren Conrad and former fellow The Hills star Stephanie Pratt make a stylish statement at the Hyde Bellagio celebration in Las Vegas, where Leona Lewis, Wilmer Valderrama and Eliza Dushku were among the revelers. 12 of 18 QUITE A CONTRAST! Michael Tran/WireImage Also partying at the Hyde Bellagio, a white-hot Sofia Vergara strikes a pose with a darkly dressed Joe Jonas – but was he as entertaining as Kermit the Frog? 13 of 18 ICING ON THE CAKE Angela Weiss/WireImage Singer Bruno Mars caps off a blockbuster year – which included winning a Grammy, a Billboard Music Award and an American Music Award – with a sweet celebration at Las Vegas's The Bank Nightclub at the Bellagio. 14 of 18 COLD SHOULDER Neilson Barnard/Getty Shameless star Emmy Rossum turns up the heat in a strapless red dress during an appearance on NBC's New Year's Eve with Carson Daly in N.Y.C. 15 of 18 HOST WITH THE MOST Gustavo Caballero/Getty A dashing Sean greets his guests, which include actress Vivica A. Fox (pictured), Gayle King and Star Jones, at the CIROC: The New Year 2012 bash in Miami, held at a private estate. 16 of 18 GETTING CHEEKY Ethan Miller/Getty Someone's feeling frisky! Brandy gives a peck to reported new beau Ryan Press at The Cosmopolitan of Las Vegas Celebrates New Year's Eve party, where music legend Stevie Wonder was the star attraction. 17 of 18 HATS OFF! David Becker/WireImage After showing off her ice-skating skills, Holly Madison flaunts her famed figure while welcoming 2012 at the Chateau Nightclub amp Gardens in Las Vegas. 18 of 18 LOCKING HORNS David Becker/WireImage Also at Sin City's Chateau Nightclub amp Gardens, an expectant Kourtney Kardashian and baby daddy Scott Disick herald the new year by tooting a tune.