Before Justin Bieber, Harry Styles and Taylor Swift, we had these guys. From 1990s heart-throbs (step forward Jason Priestley) to the twins we wanted to BE (thanks to Sweet Valley High) see how your favourite teen stars of yore have grown up - and discover what some of today's celebrities were doing in their younger years in the gallery below.
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Picture credits: Rex Features
Teen Idols then and now: Jason Priestley
Then: The blue eyed, dreamy moral compass of game-changing teen drama Beverley Hills 90210, and star of the music video for I Drove All Night.
Now: A little more rugged around the edges, Priestley is currently starring in Canadian TV series Call Me Fitz, about a morally bankrupt car salesman forced to become business partners with his inner conscience.
Teen Idols then and now: Claire Danes
Then: Played the auburn-haired angsty teenager Angela in 'My So-Called Life
Now: Playing blonde-haired troubled CIA officer Carrie in excellent TV drama Homeland.
Teen Idols then and now: Jared Leto
Then: Our number 1 TV crush, bad boy Jordan Catalano in My So-Called Life
Now: Sports a mohawk, is in the band 30 Seconds to Mars, and has a website called Notes From the Outernet
Teen Idols then and now: Aaron Carter
Then: The cherubic pre-teen pop sensation was known for hits Crazy Little Party Girl Crush on You and I Want Candy, before dating Lindsay Lohan and Hilary Duff in his teens
Now: Was arrested for speeding, appeared on Dancing with the Stars and is recording his new album The After Party
Teen Idols then and now: Sara Gilbert
Then: Played artistic, sarcastic teen Darlene in Roseanne - had an excellent collection of check shirts.
Now: She has appeared in The Big Bang Theory, and is co-host and executive producer of The Talk, a chat show also starring Sharon Osbourne.
Teen Idols then and now: Hanson
Then: Blonde, long-haired brother Hanson shot to fame with single MMMbop in 1997, and their debut album Middle of Nowhere sold 10 million copies worldwide.
Now: Still releasing material, in 2012 the band toured with Canadian teen star Carly Rae Jepsen.
Teen Idols then and now
Then: Cheeky chappies PJ and Duncan were the stars of Byker Grove, (who could forget the freak paint-balling accident storyline) and went on to release hit pop singles such as U Krazy Katz and Let's Get Ready To Rhumble
Now: Known by their true names, Ant and Dec, the award-winning duo have presented pretty much every hit talent/game show on ITV, bar The X Factor.
Teen Idols then and now: Anna Chlumsky
Then: The star of weepy sleepver classics My Girl and My Girl 2
Now: The star of sweary, hilarious political satire Veep
Teen Idols then and now
Then: The long-haired one on alien-themed sitcom 3rd Rock from the Sun - and a few years later - the nerdy nice one (who gets the girl) in 10 Things I Hate About You
Now: Inception, The Dark Knight Rises, Looper - Joseph became a bona fide movie star, via indie flicks like 500 Days of Summer
Teen Idols then and now: Tia and Tamera Mowry
Then: With their jaunty hat choices, hilarious parents Lisa and Ray, and boy troubles ("Go HOME Roger!"), Tia and Tamera in Sister Sister were our favourite teen twins on TV (aside from Sweet Valley High).
Now: The twins are now reality TV stars - with their own reality show Tia and Tamera on the Style network in the US.
Teen Idols then and now: Cynthia Daniel and Brittany Daniel
Then: Starred as Jessica and Liz Wakefield in the TV series of Francine Pascal's Sweet Valley High books. Had amazing 90s style and a catchy theme tune.
Now: Cynthia retired from acting after the show was cancelled and became a photographer. Brittany has appeared in Dawson's Creek, That 70's Show, and It's Always Sunny in Philadelphia
Teen Idols then and now: Mark-Paul Gosselaar
Then: The blonde-haired, wise-cracking star of Saved by the Bell, Zach Morris.
Now: Brown-haired star of legal comedy Franklin & Bash. Competes in triathlons.
Teen Idols then and now
Then: Dustin played goofy, loveable class geek Screech in the Saved by the Bell TV series and various spin-offs.
Now: After the show, Dustin became a touring stand-up comic, starred in his own sex tape scandal, appeared on various reality shows and released a tell-all book Behind the Bell.
Teen Idols then and now: Melissa Joan Hart
Then: The star of two classic teenage TV shows - Clarissa Explains It All and Sabrina the Teenage Witch
Now: Stars in TV series Melissa and Joey with Joey Lawrence - who was also in hit teen show Blossom.
Teen Idols then and now: Larisa Oleynik
Then: The star of TV series The Secret World of Alex Mack, films 10 Things I Hate About You and The Babysitters Club.
Now: Appeared in Mad Men as Cynthia Cosgrove.
Teen Idols then and now: Neil Patrick Harri
Then: Played a child genius/ teenage doctor in Doogie Howser, M.D
Now: Plays womanizing Barney Stinson in How I Met Your Mother
Teen Idols then and now: Callan Mulvery
Then: Heartbreak High was a gritty Aussie teen drama, and Callan played rebellious, roller-blading hearthrob Bogdan Drazic.
Now: Callan had to have extensive facial surgery after a horrific car crash in 2003. His acting career continued, however, and he's still a huge star in Australia thanks to crime show Underbelly.
Teen Idols then and now: Jason Donovan
Then: Played Scott in Neighbours, before becoming a pop sensation - his debut album Ten Good Reasons was one of the highest-selling albums of 1989.
Now: After battling with a drug problem throughout the 1990s, Jason is now still releasing albums, has a radio show on Heart FM and was a judge on ITV's Superstar this year.
Teen Idols then and now: Jesse Spencer
Then: Another Neighbours heartthrob - Jesse played Billy, Doctor Carl Kennedy's son
Now: Jesse moved to LA and won a major role in TV series House
Teen Idols then and now: Kylie Minogue
Then: Before she became an international pop icon, Kylie started out as girl-next-door Charlene on Neighbours
Now: Need we explain how things turned out?
Teen Idols then and now: Mayim Bialik
Then: Mayim tap-danced her way into our hearts in teen sitcom Blossom.
Now: She's Dr. Amy Farrah Fowler in The Big Bang Theory
Teen Idols then and now: Michelle Williams
Then: Michelle started out as cynical, 'out of control' city girl Jen ( Joey's rival), on Dawson's Creek.
Now: An academy award nominated actress for roles such as My Week with Marilyn and Blue Valentine.
Teen Idols then and now: Molly Ringwald
Then: Molly was the girl in the 80's Brat Pack gang we all wanted to be, thanks to her roles in Pretty and Pink and The Breakfast Club
Now: She plays a mother in American drama The Secret Lives of an American Teenager
Teen Idols then and now: Paul Nicholls
Then: He first caught our eye in performing arts drama The Biz, before progressing to full on teen heartthrob status in Eastenders.
Now: The curtains have gone, and now he's starring in dramas like Law and Order: UK and Holby City.
Teen Idols then and now: Rob Lowe
Then: He was the Brat pack heart hrob every girl in the eighties loved, even with a mullet. Plus he played a mean saxophone in St Elmo's Fire.
Now: His piercing blue eyes returned to our screens (but his mullet didn't) in The West Wing, Brothers and Sisters and Parks and Recreation.