Justin Theroux knows acting ‘isn’t brain surgery’

We can’t really talk to Justin Theroux about “The Girl on the Train.” In the movie version of the mega-bestseller, the actor and writer plays Tom, the ex-husband of Emily Blunt’s public transit-riding voyeur, and one of several potential perpetrators in the missing person case that forms the plot. Most of his big stuff doesn’t happen until the third act, and we’d never dream of spoiling it (even though so many readers already know what happens). But there’s plenty of other things to talk about. Theroux, 45, is a renaissance man: he stars in “The Leftovers,” and co-wrote “Tropic Thunder” and “Zoolander 2.”

We talked to Theroux about refraining from spoilers, actor cliches and David Lynch.

Since we can’t say much about your character, we can talk about Emily Blunt’s protagonist. I found it was an empathetic portrayal of someone who’s a hot mess, as well as a voyeur, which is usually portrayed as creepy.
But that’s something we all do anyway. You ride the subway and stare across the aisle. We think, ‘They’re probably this or that.’ We probably don’t do it to the extent that she does, but we do it every day. It’s human nature.

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I feel like journalists and actors and writers are the only people who can people-watch and not seem creepy. It’s like, “We’re just doing our job!”
Exactly. It’s about observation. It’s important to stay street-level and listen to strangers — to a tolerable degree, if someone’s allowing me to. I know that sounds like a dumb actor thing to say.

Do you hate actor-speak — when actors wax poetic on their “craft”?
Yeah. That’s why I love watching James Lipton. It’s a s—tshow every show. I love watching DVD extras, particularly war movies, where the actors say, “Oh, we were in a war!” No. It’s our job to pretend to make some faces. That’s it. [Laughs] Just say the words that other people wrote. It’s not like we’re doing brain surgery.

Writers’ jobs are way harder.
Way harder. Acting is a dessert compared to creating a f—king entree. When actors get scripts and they say, “Yeah, I don’t think I’d say this,” or “I don’t think I’d do that,” it’s like, “Really? Because you didn’t come up with it. And I thought you would.” No one does a Mamet play and goes, “You know what? I’m just gonna riff on this!” Movies and television are, for some reason, the only mediums where actors can say, “I want to change this.”

It sounds like you don’t have a lot of actorly ego.
I don’t! I don’t even have a lot of writerly ego.

You were in David Lynch’s “Mulholland Dr.” With Lynch, you definitely can’t act like a prima donna.
With David no one has actorly ago. If you did, he wouldn’t hire you in the first place. And David’s not known for his sparkling dialogue. He has some of the weirdest lines you’ll ever say. You say them and he’ll do the rest, because he’s a beautiful filmmaker. You work with auteurs like him and you wouldn’t dare take credit for [the work].

“Mulholland Dr.” was recently voted in a critics poll the best film of the 21st century so far.
I saw that! I’d say, “Yeah, it’s a great film,” and I realize I did nothing to make it that way. That’s top to tail his invention. I was just servicing his thing. I feel the same way about Damon Lindelof [creator of “The Leftovers”]. I can take very little credit for it because so much of that came from that guy’s brain. I just help present it to people, but he’s the guy who created it.