December 18th is a star-studded occasion when it comes to celebrating birthdays. Today, a trio of prominent celebrities are celebrating their big days — none other than Brad Pitt, Katie Holmes and Christina Aguilera.

As the male portion of Brangelina, Brad Pitt is a Hollywood heart-throb best known for his roles in "Fight Club," the "Ocean's Eleven" movies and his Academy Award nominated performance in "The Curious Case of Benjamin Button."

But his most important movie role to date is undoubtedly "Mr. and Mrs. Smith," where he met and fell in love with co-star and current romantic partner Angelina Jolie. Hopefully Brad gets to enjoy some more movie success during the upcoming award circuit with "Inglourious Basterds,", the World War II movie he starred in for director Quentin Tarantino.

Katie Holmes, meanwhile, is no stranger to famous romantic couplings herself. The former "Dawson's Creek" actress's marriage to actor Tom Cruise is hardly a secret from the moviegoing public, nor is their adorable daughter Suri. Following the birth of Suri, Katie took a lengthy break from acting, though she's getting back into the game with the upcoming "Don't Be Afraid of the Dark" and "The Romantics."

Moving over from the realm of moviemakers to musicians is Christina Aguilera, celebrating her 29th birthday today. From her earliest days on the Mickey Mouse Club to the resounding success of her recent album Back to Basics — not to mention her own foray into the film world with next year's "Burlesque" — Christina is undoubtedly a talent that likes to keep things busy. Here's wishing all three of them a happy birthday from the Hollywood Crush gang.