1Dylan O'Brien: Then
Tiffany Rose//Getty Images 2Dylan O'Brien: Now
Jon Kopaloff//Getty ImagesIf Taylor Swift casts you as one of her exes in a music video, you're major celeb crush material.
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3Tyler Posey: Then
Tiffany Rose//Getty ImagesWhen it comes to teen werewolves, Tyler always ranked a very close second behind Taylor Lautner.
4Tyler Posey: Now
Irvin Rivera//Getty ImagesHe's entering his Bad Boy Tyler phase!
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5Harry Styles: Then
Neil Mockford//Getty ImagesHe lit up our worlds like nobody else. Sorry to Louis, Niall, Liam, and Zayn.
6Harry Styles: Now
CBS Photo Archive//Getty ImagesTo borrow a phrase from Lady Gaga: "Talented, brilliant, incredible, amazing, showstopping, spectacular, never the same, totally unique, completely not ever been done before."
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7Avan Jogia: Then
Chelsea Lauren//Getty ImagesIf you wore studded belts, drew on your Converse with a Sharpie, and listened to a ton of pop punk, you probably had an Avan Jogia phase.
8Avan Jogia: Now
Daniele Venturelli//Getty ImagesStill broody as ever, but now he's a model.
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9Donald Glover: Then
NBC//Getty ImagesTroy Barnes was the best (and cutest!) character on Community, and you won't change my mind.
10Donald Glover: Now
Momodu Mansaray//Getty ImagesChildish Gambino became Grown Man-ish Gambino right before our very eyes.
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11Justin Bieber: Then
Kevin Winter/DCNYRE2013//Getty ImagesHigh hair, hooded vest, rhyming "swag on you" with "fondue"...peak Bieber Fever era.
12Justin Bieber: Now
Kevin Winter//Getty ImagesHe's since gone from "Boyfriend" to Hailey's husband. Still the swaggiest in my book.
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13Big Time Rush: Then
Jeffrey Mayer//Getty ImagesIf you didn't learn the choreo to "Boyfriend" and never screamed your lungs out at one of their concerts, you haven't lived.
14Big Time Rush: Now
John Lamparski//Getty ImagesStill making (really catchy) music—and still hot. James, you'll always be my favorite.
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15Austin Butler: Then
Rob Kim//Getty ImagesThere was a time when Austin was just a Nickelodeon actor-turned-boyfriend of Vanessa Hudgens.
16Austin Butler: Now
Jeremy Chan//Getty ImagesYou might have heard that he played Elvis Presley, one of the hottest celebs of all time, in 2022. Talk about a transformation.
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17Liam Hemsworth: Then
NBC//Getty ImagesIf you claim you weren't jealous of Miley Cyrus for getting to date him, stop lying to yourself.
18Liam Hemsworth: Now
John Sciulli//Getty Images Advertisement - Continue Reading Below
19Ross Lynch: Then
Eric McCandless//Getty ImagesHe might have had this really bright hair color back in the day, but he was still pretty cute.
20Ross Lynch: Now
Dia Dipasupil//Getty ImagesMuch better! Loving the hipster-slash-hippie vibe he's got going on here.
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