Photo: Julia Roberts arrives at the Metropolitan Museum of Art's Costume Institute Gala, in New York on Monday, May 5, 2008.
Tom CruiseThe actor's career and public image has had some highs and lows, but he still has that same smile that caught America's attention in films like "Risky Business" and "Top Gun."
Photo: Tom Cruise attends the premiere of his film "Valkyrie" in New York on Monday, Dec. 15, 2008.
Brad Pitt And Angelina JolieThey're one of the most beautiful couples in Hollywood, and their good looks (including their grins) have graced many a movie screen and magazine cover.
Photo: Brad Pitt, right, and actress Angelina Jolie pose for photos on the red carpet during a premiere of Pitt's film, "The Curious Case of Benjamin Button," in Tokyo, Japan, Thursday, Jan. 29, 2009.
The Mona LisaHer shy, subtle smile may be one of the most famous grins in the entire world.
Photo: Mona Lisa (La Gioconda), by Leonardo da Vinci (Italian, 1452-1519).
Princess DianaThe late princess' smile, along with her beauty and humanitarian efforts, captured the adoration of her country and the entire world.
Photo: Princess Diana arrives at a benefit for breast cancer research in Washington on Sept. 24, 1996.
George ClooneyClooney's grin is just one of the reasons he regularly appears on lists of sexy male stars.
Photo: George Clooney makes an appearance on NBC's "The Today Show" in New York on Thursday, April 3, 2008.
Reese WitherspoonFrom "Legally Blonde" to her Oscar-winning turn in "Walk the Line," Witherspoon has captured audiences with her acting chops and bright smile.
Photo: Reese Witherspoon leaves a taping of "The Late Show with David Letterman," Tuesday, Nov. 25, 2008, in New York.
Will SmithSmith's broad grin has taken him from "The Fresh Prince of Bel-Air" to bona-fied movie stardom.
Photo: Will Smith poses on the press line at the premiere of the film "The Women" in Los Angeles on Thursday, Sept. 4, 2008.
Miley CyrusShe's only a teenager, but Miley has already become a superstar -- thanks to "Hannah Montana," her music career and her bright smile.
Photo: Miley Cyrus poses for photographers on the red carpet at the premiere of "Hannah Montana the Movie" in Los Angeles on Thursday, April 2, 2009.
Zac EfronEfron burst onto the scene with his dance moves - and his charismatic smile - in Disney's "High School Musical" series. Now, the heartthrob is a Hollywood regular.
Photo: Zac Efron smiles during a press conference to promote his film, "17 Again," in Tokyo, Japan, Thursday, May 14, 2009.
Patrick DempseyThe "Grey's Anatomy" star's sexy smile is part of what makes him so "McDreamy."
Photo: Patrick Dempsey attends the Whitney Museum of American Art's gala on Monday, Oct. 20, 2008 in New York.
Farrah FawcettShe will always be famous for her long blonde hair, but her wide grin is another reason why the "Charlie's Angels" star became an icon.
Photo: This 1977 file photo provided by ABC shows actresses Kate Jackson, Jaclyn Smith and Farrah Fawcett, from left, as private investigators in the television series "Charlie's Angels."
Jim CarreyCarrey's wide grin and humorous movie antics can put a smile on anyone's face.
Photo: Jim Carrey, who narrates the IMAX film "Under the Sea 3D," jokes with fans at a special screening of the film at the California Science Center IMAX theater in Los Angeles, Thursday, Feb. 5, 2009.
Marilyn MonroeMonroe's sexy look and endearing smile made her a star during her lifetime and an icon after her death.
Photo: Marilyn Monroe with second husband and baseball legend Joe DiMaggio in New York, June 1, 1955.
America FerraraShe may play "Ugly Betty" on television, but in person Ferrara is nothing short of beautiful -- especially when she is smiling for the cameras.
Photo: America Ferrara arrives at the InStyle and Warner Bros. Studios Golden Globes after-party on Sunday, Jan. 11, 2009, in Beverly Hills, Calif.
Justin TimberlakeNow a sexy solo star, JT has been making girls swoon with his singing voice and his smile since his days with the pop group 'N Sync.
Photo: Justin Timberlake walks the red carpet at the Conde Nast Media Group's Fifth Annual "Fashion Rocks" event at Radio City Music Hall in New York on Friday, Sept. 5, 2008.
Audrey HepburnHepburn's fashion sense made her a style icon, but her bright smile is also part of what made her a star.
Photo: Actors Mel Ferrer and Audrey Hepburn arrive in Rome just after they were married, on Sept. 29, 1954.
Kate MossThe supermodel has been featured in many ad campaigns and magazine covers, but she looks her best when she's smiling.
Photo: Kate Moss arrives at the 7th on Sale dinner gala to benefit the fight against HIV and AIDS on Thursday, Nov. 15, 2007, in New York.
Carrie UnderwoodUnderwood won over the country on "American Idol" with her big voice and bright smile and has gone on to become an award-winning country music star.
Photo: Carrie Underwood arrives at the 51st Annual Grammy Awards on Sunday, Feb. 8, 2009, in Los Angeles.
Halle BerryThe Oscar-winning actress has been featured on many a "Most Beautiful" list, in part because of her gorgeous smile.
Photo: Halle Berry arrives at a screening of the film "X-Men Origins: Wolverine" in Los Angeles, Tuesday, April 28, 2009.