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It might have been his breakout role in Summerland that hooked you. Or perhaps it was his three-time turn as Troy Bolton in the High School Musical series that made you a fan. If not, you probably jumped on the Zac Efron bandwagon after his starring roles in movies like 17 Again, New Year's Eve or The Lucky One. Regardless of why you're a fan, we can't blame you for loving this Hollywood heartthrob, who turns 26 on Oct. 18. Here's a look at how Zac has changed through the years.
Jean-Paul Aussenard/WireImageAlthough Zac's career began with small guest spots (on TV shows like ER and CSI: Miami), his breakout role came on The WB's Summerland, on which he played Nikki's (Kay Panabaker) boyfriend, Cameron Bale. His most successful years were yet to come, but with those baby blues, Zac already had America in the palm of his hand.
Michael Bezjian/WireImageIt looks like life does imitate art after all: As they approached superstar status, Zac and High School Musical costar Vanessa Hudgens began dating. For the next four years, it was impossible to find a picture of the couple that wasn't adorable.
Stephen Shugerman/Getty Images; John Sciulli/WireImageWhat a difference a haircut can make! In 2006, Zac traded in his trademark shaggy blond 'do for a darker, closer cut. One thing that didn't change: his trademark smirk.
Kevin Mazur/WireImageIn addition to being a wildly successful movie star, Zac can hardly complain about his costars throughout the years. In 2007, he traded in Hudgens and Ashley Tisdale for Nikki Blonsky, a former Coldstone Creamery employee whose big break came via the leading role in Hairspray. If being an overnight success weren't enough to make us green with envy, working alongside Zac for a year definitely is.
Ferdaus Shamim/WireImageLong hair no more! As the High School Musical film trilogy came to a close, Zac's big-screen career really took off. What better way to celebrate a new life chapter than a new haircut? And even though Zac gained a huge fanbase with his long hair, dare we say the short 'do suits him better?
Jason Merritt/Getty ImagesEven after their Wildcat days were over, Zac and Vanessa stuck together in front of and behind the camera. Although they ultimately called it quits in 2010, the pair looked as seasoned and glamorous as ever at the 2009 Golden Globes in Beverly Hills.
Jason Merritt/Getty Images for VH1If there's anyone who can pull off a suit on the red carpet (on par with Ryan Gosling, at least), it's Zac! And he had plenty of red carpets to walk as he grew older, maintaining a healthy career that included one of his most dramatic roles, as the title character in 2010's Charlie St. Cloud.
Henry S. Dziekan III/Getty Images for IMGScroll back up to the top of this page, and the eager 17-year-old you'll find there is barely recognizable! Just seven years later, Zac had matured a remarkable amount, shooting the cameras a smoldering gaze at an N.Y.C. Fashion Week show in 2011.
Jason Merritt/Getty ImagesFirst musicals, then comedies, then dramas... then romantic comedies. Zac took the plunge into the rom-com genre in 2012, opposite Orange Is the New Black's Taylor Schilling in The Lucky One. And while we never would have pegged Zac as the type to slick his hair back, we can't deny how suave he looks at the film's Hollywood premiere.
On his 26th birthday, Zac looks as professional and sexy as ever. Now sporting a short wavy 'do and an even bigger collection of dapper suits, Zac remains one of Hollywood's hottest heartthrobs -- and his phenomenal success isn't too shabby, either.
Rebecca Iannucci is an iVillage contributing writer. Follow her on Pinterest, Twitter and Google+.