Prepare to feel old. The actors you are about to see have combined for numerous Oscar nominations, hundreds of magazine covers, and billions in box office earnings – all before reaching the quarter-century mark.

Zac Efron

• Age: 21.

• Years on list: 2007, 2008, 2009.

• What he’s done: He of the perfect hair sang and danced his way to superstardom in ‘High School Musical’ (with ‘HSM’ 3? even hitting the big screen) before branching out in the ‘Big’-like hit ‘17 Again.’

• What’s next: Will prove he’s got dramatic chops in November’s ‘Me and Orson Welles’ (directed by Richard Linklater); then takes two title roles, in the drama ‘The Death and Life of Charlie St. Cloud,’ and the video-game adaptation ‘Johnny Quest.’

• Industry buzz: “Not only is he hotter than ever as he grows into a sexy leading man, but his career already has more staying power than many of his ‘HSM’ co-stars… Zac has shown that while he’s a very pretty face, he’s also all about being a hard worker and stretching his acting skills like his career mentor Leonardo DiCaprio.”