One of the toughest things to guess about a celeb is age. In fact, the older they get, the younger they sometimes look!

For instance, would you have guessed that the gorgeous Padma Lakshmi will turn 40 this year, come September 1? The Top Chef, who is expecting her first baby, looks svelte even when she's surrounded by all that yummy food.

Here's a look at some other Hollywood stars, who will turn 40 this year, but look way younger!

Birthday: October 8

Turning 40 hasn't robbed The Bourne Identity star of his boyish charm so evident in one of his early films, Good Will Hunting.

Birthday: March 7

She's one of the reasons why we loved the first two Mummy movies. That adorable English accent just makes her that much hotter.

Birthday: April 29

She singlehandedly made yellow jumpsuits very sexy. As a matter of fact, it's about time we see her in one again. Tarantino, are you listening?

Birthday: November 6

This actor, writer and director's good looks and acting skills are reasons why we've almost forgiven him for breaking up with his wife Uma Thurman.

Birthday: January 29

Now that this hottie is 40, we hope to see her play other roles than just the ditzy blonde she's so adept at playing.

Birthday: March 28

Yep, he's turning 40 too. But he's off the market, girls.

The Break Up star, who has been linked to Jennifer Aniston in the past, married his girlfriend Kyla Weber at a secret wedding which reportedly took place at Arnour House at Lake Forest Academy in Lake Forest, Illinois, on January 2.

Birthday: December 12

The face of Revlon cosmetics is more than just a pretty face. Just watch A Beautiful Mind and you'll know why.

Birthday: May 18

Television's most powerful woman -- after Oprah Winfrey, of course -- makes 40 rock. After all, how many 40-year-olds have one of the world's sexiest men -- Robert Pattinson -- panting after her?

When asked about what 'type' of girls he would like to date, the 22-year-old Twilight heartthrob took Fey's name. 'I don't really have a 'type' but I like smart people. I really like Tina Fey -- she is, like, the sexiest woman,' the New York Daily News quoted Pattinson as saying.

Birthday: March 18

Like wine, the rapper-turned actress just seems to get better with age.