From awkward kids to major hotties: our favourite heartthrob transformations

Happy 25th birthday to Zac Efron! That's right that gawky kid from High School Musical is a whopping quarter-of-a-century today. And man, isn't he one hunk of man now!

We've watched many child stars grow up onscreen, but while most end up passed out in a gutter surrounded by Teen Choice surf boards from their glory days, some of the luckier ugly ducklings blossom before our very eyes into bona fide stud muffins. Yes, we're talking about the more overlooked male celebrities, the guys who've gone from lean to mean with a little help from the weight lifting machine.

Just check out our favourite celebrity transformations, going from awkward early years, to sugary eye candy so sweet they'll give you a toothache just for looking (or should that be eye-ache?):