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One reviewer of Dempsey's 1987 teen comedy Can't Buy Me Love called the actor (left, that year) "as appealing as mulched lawn." "I haven't recovered from that," says Dempsey, 39. It must help to know he's TV's latest hot doctor, thanks to his ABC hit Grey's Anatomy. And he's getting rave reviews from one special fan: "One day my 3-year-old daughter (with wife Jill) said, 'You're very handsome, Poppy.' That was the best compliment ever."
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In his breakout role in 1995's To Die For (left), Phoenix was still best known as the younger brother of the late actor River. Now, playing Johnny Cash in the upcoming Walk the Line, Phoenix, 31, has finally arrived as a leading man – and a thinking woman's heartthrob. "Joaquin is absolutely stunning and a brilliant actor," says singer Charlotte Church. "He seems like a bit of an introvert, and I just think that is so cool."
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Even PEOPLE's two-time Sexiest Man Alive went through an awkward stage: Witness his feathered mullet (left, in 1987). "He had more pounds on him then, and he wasn't as good-looking," says Ivana Chubbuck, Pitt's acting instructor in the late 1980s. Luckily, he's aged very gracefully: "He's like this lumberjack mountain man," Jessica Biel told PEOPLE. "He's like a rough pretty boy. I've always thought he was just absolutely gorgeous."
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Timberlake (left, in 1998) made millions of girls scream as a member of 'N Sync, but these days, the multiplatinum-selling solo artist and film actor (in the upcoming Edison and Alpha Dog), now 24, appeals to women of all ages – and not just girlfriend Cameron Diaz, 33. Diaz's In Her Shoes costar Shirley MacLaine admits, "He's young and good-looking and knows about wardrobe. That's all I know."
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Fox (left, in the early '90s) first won hearts as Charlie Salinger on the family drama Party of Five. Now 39, he's making viewers swoon again as sensitive Dr. Jack Shepard on ABC's hit Lost. But this time, he's more comfortable with himself – and his celebrity. "I fought fame for a long time," he says. "I was very distrustful of people. I was isolating myself. I've grown up a bit."
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On the '90s sitcom The Fresh Prince of Bel-Air, Smith (in 1990, left) was cute and goofy – but at 37, he's far sexier as a devoted dad (to sons Trey, 13, and Jaden, 7, and daughter Willow, 5) and husband to Jada Pinkett Smith. Consider his and Jada's best Valentine's Day: "We went to Hawaii and had seven days of Valentine's Day," he says. "Flowers, candy, petals in the bathtub – each day was sweeter than the next."
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Bateman (left, in 1994) was a teen idol on the '80s shows Silver Spoons and The Hogan Family – and now, at 36, he's a Golden Globe winner for his role on FOX's quirky Arrested Development. "My fans all have teenage girls of their own now, so that's a little disconcerting," he says. "I don't have any crazy fan encounters anymore. They walk now instead of run, and they're very kind."
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NEIL PATRICK HARRIS
Harris (left, in 1994) has come a long way since his dorky Doogie Howser, M.D days. As wannabe ladies' man Barney on CBS's How I Met Your Mother, Harris, 32, gets to show his comedy chops ("I have to tread the line between cool and jackass," he says) and sport Barney's trademark tailored look: "I'm a jeans and T-shirt guy for sure, but I like the suits. Today I wore Dolce amp Gabbana. It's very exciting."
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He first shook his bon-bon as a member of Menudo (left, in 1988), and now Martin, 33, is rocking his spiritual side on his new album, Life. In the six years since his self-titled solo debut, he traveled, did philanthropic work and learned to appreciate the important things: "When I freak out," he tells PEOPLE, "I say to myself, 'Dude! Relax! Grab a paper and a pen and just write 10 things you are grateful for.' "
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Talk about all grown up: O'Connell, 31, has transformed himself from the chubby kid in 1986's Stand by Me to the boy-next-door in 1993's Calendar Girl (left) to the chiseled star of NBC's Crossing Jordan. "He has the most beautiful body I've ever seen!" says fiancée Rebecca Romijn.
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It's hard to believe now, but when Clooney played handyman George Burnett on The Facts of Life from 1985-86, "None of the characters had any attraction to him – that wasn't how his part was written," says costar Lisa Whelchel. "But I have to say, he has matured physically and professionally very well." That's an understatement. Now 44, Clooney, says his former ER love interest Julianna Margulies, "just gets better with age."