Thomas Dekker dreads birthdays. Every year he makes a mental list of everything he wants to accomplish over the next 12 months, and every year he says there are 20 things he didn’t get done. Only months away from his 21st birthday, Dekker has accomplished more personal goals than most of his middle-aged peers, with plenty left to tackle.

“I’m sure that’s too much of an overachiever attitude, but that’s the truth,” he says.

A working actor since the age of 5, Dekker didn’t really appear on the pop culture radar until landing the role of Zach, the cheerleader’s best friend on “Heroes.” Dekker left the show to play John Connor on Fox’s “Terminator: The Sarah Connor Chronicles,” leveraging that exposure to pursue his varied career interests.

In addition to the show, he has somehow also found the time to record two albums (with another in production), act in horror movie “Laid to Rest” and ensemble drama “My Sister’s Keeper” and write a directorial debut, “Whore” — with another eight screenplays “mapped out completely in my head.”

“Whore” began modestly enough, with Dekker using a 16mm camera to document street prostitutes, then snowballed as showbiz friends Rumer Willis, Brad Rowe and Megan Fox joined in. Dekker is tweaking “Whore” for possible festival play, but warns, “It’s a tough film for people to handle because it’s very aggressive and provocative and dark.”

After pushing himself hard throughout his teens, Dekker sounds almost satisfied with 20. “It’s been a year where ‘Terminator’ has given me such an entrance into the public eye with everything else I want to do,” says the actor, who will soon be combining his music and acting talents in “Fame.”

“This is the first year where I feel like, ‘I made a lot of things that are being heard, that are being seen,'” he says. “That’s a really nice feeling.”

Recent breakthrough: Leapt from “Heroes” to Fox’s “Terminator: The Sarah Connor Chronicles.” “I felt if I signed on, if it was successful, it would really kind of change everything, which it has.”

Role model: “River Phoenix. I watched all of his films and thought he did some really revolutionary stuff for his age.”

What’s next: Plays a supporting part in Nick Cassavetes’ “My Sister’s Keeper,” followed by a lead role in ensemble tuner “Fame.”