World's Most Beautiful 2010!

At 42, the mother of three (twins Hazel and Phinnaeus, 5, and Henry, 2) is celebrating her fourth turn as the cover girl for PEOPLE's Most Beautiful. While the star of the upcoming film Eat, Pray, Love is as lovely as ever, old pal George Clooney says he knows her secret. "It has nothing to do with the way she looks," he says. "It has everything to do with who she is."

VIDEO: Julia's Changing Looks

He is Hollywood's leading man in uniform. So how does the Dear John star, 30, maintain that ripped army-issue physique? "Do I get massages? Hell yeah, I get massages!" he says. "Are you kidding me? I wanna get one right now! Where's a masseuse?"

The mega-success of Avatar has landed the native New Yorker on red carpets all over the world – and on countless best-dressed lists. Her secret to mastering the red carpet? "I have learned to have at least one arm on my waist," Saldana, 31, tells PEOPLE. "And I have also learned not to talk when I'm am posing."

VIDEO: Why Being Blue Was Beautiful

Dubbed a "bombshell" when she was just a teen, Johansson, 25, has two must-have beauty staples: "Red lipstick and sandwiches." That's not surprising to her Iron Man 2 director Jon Favreau, who says that "when you're hanging out with her on the set, she's just like one of the guys."

He plays the adventurous – and buff! – Prince of Persia this summer, but off-screen the actor, 29, is a regular guy who doesn't need much to make him happy. "I feel my best after a home-cooked meal with family and friends," he says.

"I feel beautiful when I'm laughing and surrounded by friends that know me and love me and vice versa," says Aniston, who celebrated her 41st birthday in February with good pals Courteney Cox and Sheryl Crow in Mexico. "A good body scrub and massage do the trick as well."

The Modern Family star has her own family secret: She's not actually a brunette. "My natural hair color is blonde," says the Colombian beauty, 37. "It didn't match the Hollywood stereotype for a Latina woman." Not that she minds the tress-formation: "I think I should have always had dark hair."

"I always wanted brown curly hair, brown eyes and dark skin. That's because I grew up in an Italian family and wanted everything I didn't have," admits the Philadelphia native, 35. "I was about 29 when I realized that all I've got is this, so I might as well figure out what [this] is."

Love has only made the engaged pop star, 25, more confident. Before British comic Russell Brand was in the picture, "I didn't feel very beautiful without a ton of makeup," Perry tells PEOPLE. "When I have no makeup on, which is rare, he tells me I look like the most beautiful girl in the world."

VIDEO: Katy Perry's Proud of Her Curves

From playing a bookworm (Jennifer's Body) to a prostitute (Chloe), the actress, 24, has proved herself a chameleon. So she welcomes seeing a familiar face every day – her own. Seyfried tells PEOPLE: "When I wake up in the morning and I don't have any makeup on, I don't feel ugly. I just feel clean."

The secret to the singer's "swoosh"? "I spend five minutes on it," he says."I use shampoo, conditioner – basically whatever is in the hotel – and blow-dry." That three-step routine has tweens swooning over the 16-year-old, who insists the do does not make the man: "It's part of my image; it's not who I am."

"In a strange way, I feel younger now than I did on ER," says the star of The Good Wife, 43. "Now, I'm doing what Julianna would want to be doing as opposed to what everyone else thinks I should be doing. That's the difference in getting older."

"On Grey's Anatomy, you have to have make-out scenes – and it's probably best that you don't have a beer gut," says McKidd, 36, of keeping up with the McDreamys of the ER. "So I'm definitely conscious of exercise. But I like to have a Scotch at night. I'm Scottish so I'm not quite as strict."

After a hiatus to have twins Emme and Max, 2, the multi-tasking actress is back – with the Back-up Plan and a new outlook. "I can't help but be a different person now that I've had kids," Lopez, 40, has said. "That really does change your whole perspective on life for the better."

Ladies, look at your man, now back to him. Yes, the ex-football player scored a touchdown with women everywhere after starring in that unforgettable Old Spice commercial. But the low-key actor, 36, says the only pampering he does in real life is "dropping off my girlfriend in front of the nail place and then picking her up."

With her dark hair and piercing hazel eyes, the Gossip Girl beauty is often asked, "What are you exactly?" While guesses range from Puerto Rican to Brazilian, for the record the Wisconsin native, 25, says with a laugh, "I'm Hungarian and a quarter Black, so I'm a mutt."

His pale, otherworldly complexion may make girls swoon, but the British heartthrob, 23, says looking the part of a lovesick vampire in the Twilight series isn't quite as thrilling: "Having that makeup put on every single day, as soon as you get it taken off it's like, 'Oh, you do look normal. You look healthy now."

To see the full list, pick up this week's issue of PEOPLE, on newsstands now