Matt Damon, Hotties
Can you believe Matt Damon turns 40 on October 8? It seems like it was just yesterday when we saw Matt utter his first line of movie dialogue in 1988's "Mystic Pizza" at age 18. But we knew the cute Boston boy was destined for big things. Damon -- who is now happily married with two children (and a third on the way) -- nabbed a Best Original Screenplay Oscar for "Good Will Hunting" in 1997 and has starred in numerous movies including "The Talented Mr. Ripley," "The Bourne Identity" series, and "The Departed" to name a few.
 Minnie Driver, Hotties
Damon's "Good Will Hunting" co-star and former girlfriend, Minnie Driver, also turned the big 4-0 on January 31. Driver, who has a 2-year-old son named Henry, stars next in "Conviction," which hits theaters on October 15.
 Queen Latifah, Musicians
All hail the Queen! Hip-hop's first lady, Queen Latifah, turned 40 on March 18 and we think she looks better than ever.
 Tina Fey
"30 Rock" funny lady Tina Fey -- who got her start as a writer for "Saturday Night Live" in 1997 -- also became 40 and fabulous on May 18.
 Vince Vaughn 
We didn't think Vince Vaughn would ever grow up, but in 2010 the "Swingers" star, who celebrated his 40th birthday on March 28, decided it was time to settle down. He married Canadian realtor Kyla Weber on January 2
 Sarah Silverman
Sarah Silverman still has a couple of months left to savor her 30s. The sarcastic comedienne will turn 40 on December 1.
 Uma Thurman
After breaking out with the pivotal role of Ceclie in the 1988 costume drama "Dangerous Liaisons" at the age of 18, Uma Thurman was nominated for an Oscar for the 1995 cult hit "Pulp Fiction." Now 40 (her birthday was April 29), she shares two children with her ex-husband Ethan Hawke.
 Ethan Hawke
Speaking of Ethan Hawke, he'll also celebrate the big 4-0 on November 6. In addition to starring in numerous films and theater productions, Hawke -- who twice enrolled in NYU’s English program and twice dropped out -- is an accomplished author with two novels under his belt, 1996’s The Hottest State and 2002’s Ash Wednesday.
 Kelly Ripa 
Kelly Ripa entered her 40s on October 2, but the talk show host/former soap star wasn't scared about the milestone birthday. "I was much more psychologically traumatized by turning 30 than by turning 40," she said on "Live! With Regis & Kelly." "I feel very liberated by turning 40. I feel like I just don't care. I love this age. I think it's great.
 Tyson Beckford, Models
Tyson Beckford was "discovered" in 1991 by an editor from the hip-hop magazine The Source, and he's been working in the modeling industry ever since, most notably as the face of Ralph Lauren's Polo Sport. Beckford, who turns 40 on December 19, also served as a host on the Bravo reality show, "Make Me a Supermodel."
 Claudia Schiffer, Models
Claudia Schiffer blew out 40 candles on August 25. Interestingly enough, the German supermodel, who claims to be extremely shy, told Vogue, “I would never want to be in my 20s again; being very shy is quite a painful experience. Now I feel better about myself and how I am with people.”
 Naomi Campbell, Models
In May, Naomi Campbell's billionaire boyfriend Vladimir Doronin threw her a star-studded 40th birthday bash at the exclusive Hotel du Cap in Cannes, France, which included a 45-minute set by the Black Eyed Peas. Recently, the supermodel also celebrated 25 years in the modeling biz with parties hosted by Dolce & Gabbana in London, Milan, and Paris.
 Heather Graham, Hotties
For her 40th birthday on January 29, Heather Graham performed onstage with acrobatic dance troop Cirque du Soleil in Las Vegas! The actress later told the cast, "This was a blast. Even though I'm slightly afraid of heights, it was always my dream to fly onstage with Cirque du Soleil, and you've helped bring my dream to life."
 Andre Agassi, Athletes
Although he's often considered one of the greatest tennis players of all time, Andre Agassi has definitely had his ups and downs over the years -- and he didn't hold back when writing his 2009 autobiography, Open. Now clean and sober -- and happily married with two kids to fellow tennis ace Steffi Graf -- Agassi celebrated his 40th birthday on April 29.
 Lara Flynn Boyle
Lara Flynn Boyle of "Twin Peaks" fame turned 40 on March 24. The actress is rumored to be starring in an upcoming reality show for E!, which will follow her as she “splits her time between her life in Texas, her marriage to real estate investor Donald Ray Thomas II, and her Hollywood-centric lifestyle in Bel Air.”
 Jamie Kennedy
In 1997, Jamie Kennedy was playing a teen on the big screen in "Scream." On May 25 of this year, the actor, who currently provides the voice of Federline Jones on "The Cleveland Show," turned 40.
 Jennifer Connelly, Hotties
Jennifer Connelly has a few more months to go until she enters her fourth decade on December 12. The mom of two, who's married to fellow actor Paul Bettany, won an Oscar for the 2001 film "A Beautiful Mind," and will appear next in the 2001 thriller, "Salvation Boulevard."
 Padma Lakshmi, Hotties
Gorgeous "Top Chef" host Padma Lakshmi hit the big 4-0 on September 1. Can we all please look that good at 40?
 Sean Hayes
Just months before turning 40 on June 26, "Will & Grace" star Sean Hayes publicly acknowledged that he's gay, telling The Advocate magazine, "I never have had a problem saying who I am... I am who I am. I was never in, as they say. Never."
 Taraji Henson
Breaking out with her role in the 2005 indie hit "Hustle and Flow," Taraji P. Henson, who turned 40 on September 11, won an Oscar nomination for "The Curious Case of Benjamin Button," and scored a big hit this year starring as Jaden Smith's mom in "The Karate Kid."
 Chris O'Donnell, Hotties
Famous for his schoolboy roles in the 1992 films "Scent of a Woman" and "School Ties," Chris O'Donnell had a career resurgence in 2006 with a guest-starring role on "Grey's Anatomy," and now stars in the hit procedural, "NCIS: Los Angeles." The father of five turned 40 on June 26.
 Rachel Weisz, Hotties 
Oscar winner Rachel Weisz celebrated her 40th birthday on March 7. The actress best known for her roles in "The Mummy" and "The Constant Gardener," will next be seen on screen in the drama, "The Whistleblower.
 Malcolm-Jamal Warner
That's right folks, "The Cosby Show's" Theo Huxtable, aka Malcolm-Jamal Warner, turned 40 on August 18.
 Kirk Cameron
Another '80s teen star turning 40 this year? Kirk Cameron, who hit the big time at 15 playing the adorable Mike Seaver on "Growing Pains." Cameron became a born-again Christian at age 18, and in 2002, co-founded the evangelical ministry, The Way of the Master. His birthday is October 12.
Deborah Gibson, Musicians
With her first hit song, "Foolish Beat," at 17, Deborah "Debbie" Gibson became the the youngest female artist to write, record, and perform a Billboard #1 single. Gibson, who celebrated her 40th on August 31, is next set to star in a Syfy original movie entitled "Mega Python vs Gatoroid" with her teen rival, Tiffany.