St. Patrick's Day has arrived, and we're celebrating with a look at celebrities who have taken part in the fun holiday festivities over the years. For previous celebrations, Katy Perry  showed her Irish pride with a leprechaun hat, Jessica Simpson  and her fiancé, Eric Johnson, had a festive day out, and Michelle and Barack Obama had a great time in green. Keep scrolling to get a look at other stars hosting parties, attending events, and looking lucky on St. Patrick's Day!
Kate Middleton and Prince William attended a St. Patrick's Day parade in Aldershot in March 2013.
Jessica Simpson  laughed as she walked arm in arm with fiancé (and the festively dressed) Eric Johnson in LA in March 2012.
Barack Obama stopped by a bar to celebrate St. Patrick's Day in Washington DC in March 2012.
Taylor Swift  spent St. Patrick's Day enjoying a festive March doughnut in 2012.
Reese Witherspoon  went on a St. Patrick's Day run around LA in March 2011.
Beyoncé spent the lucky St. Patrick's Day holiday shopping in NYC in March 2009.
Katy Perry  threw on a leprechaun hat during her California Dreams world tour in London on St. Patrick's Day 2011.
Mariah Carey  and Nick Cannon dressed up with Roc and Roe in 2013.
Sarah Hyland and her boyfriend Matt Prokop got festive in 2013.
Carson Daly toasted to St. Patrick's Day at a pub in NYC in March 2009.
Pamela Anderson sported a green-and-white cheerleader uniform while in LA on St. Patrick's Day in March 2006.
Ashley Greene  got in the St. Patrick's Day spirit with bright green pants in March 2011 during a lunch date in LA.
Paris Hilton  left a nightclub in LA with Josh Henderson back in March 2007.
Kate Middleton sat pretty at a St. Patrick's Day event with Irish Guards in Aldershot, England, in March 2012.
Kim Kardashian  shared this picture of her and her nephew, Mason Disick, for St. Patrick's Day on her blog in March 2010.
Dave Annable spent St. Patrick's Day strolling in NYC with his mom in March 2012.
Cindy Crawford  got into the St. Patrick's Day spirit sporting a green t-shirt for an outing with husband Rande Gerber in 2013.
Matthew McConaughey  held a green carnation after a taping of Jimmy Kimmel Live in LA on St. Patrick's Day in March 2011.
Ashton Kutcher  and the late Brittany Murphy  danced at Danny Masterson's St. Patrick's Day party in LA in March 2002.
Stacy Keibler hosted the Bushmills Legends Pub St. Patrick's Day Eve event in NYC in March 2006.
Vanessa Hudgens  rocked a military-green shirt for St. Patrick's Day in March 2011 in LA.
Carmen Electra  posed on the red carpet with a neon green lollipop in March 2012 for a St. Patrick's Day event in Las Vegas.
Michelle Obama laughed with Irish Prime Minister Enda Kenny's wife, Fionnuala, during a March 2013 reception.