Justin Long is no stranger to being animated — he voices Alvin in the Alvin and the Chipmunks movies, after all — but playing a little green man in Planet 51 was still a new experience for him.

Luckily his character, Lem, the awkward teen who discovers and hides an alien (actually a U.S. astronaut voiced by Dwayne Johnson), was easy for Long to relate to. “I was — shockingly — a bit of a nerd in high school,” Long admits. “I was a little socially awkward. I wasn’t as smart, though, sadly. Lem is a lot brighter than me.”

The biggest surprise for Long was how much work he had to do to manipulate his voice to play Lem in the film, which opens next week.

“We did the movie over the course of several years, during which time I went through puberty, apparently,” Long says with a laugh. “My voice coach said that my voice over the last couple of years has gotten deeper. I don’t know what happened. But I was playing a teenager, so I pitched up.”

With 11 film credits in 2009 alone, Long has been busy — and that doesn’t count those Mac ads or his occasional pop-ins at Saturday Night Live.

He’s been seen in a number of comedies, including He’s Just Not That Into You and Funny People, but what really got the young actor some attention this year was his work in Sam Raimi’s Drag Me to Hell. But Long’s just happy he didn’t stink up the screen.

“My biggest fear was just being caught in a dishonest moment. There’s nothing worse than bad horror acting,” he says.

“I have such a respect for actors who are able to give such convincing horror movie performances. It really is exhausting, because it’s your whole body. It is just gruelling. You go home every night so drained emotionally. But in Drag Me to Hell, it was really Alison Lohman. I was just the boyfriend.”

And Long says he’s looking forward to more animation — he’ll be heard soon in Alvin and the Chipmunks: The Squeakquel — because he doesn’t have to worry so much about his hands.
“I gesticulate a lot, usually very effeminately,” he jokes. “It was a nice freedom to have in the room. I could just kind of wildly use my hands and body and not be afraid of what it looked like.”