Viggo Mortensen comes across like an international man of mystery for good reason. He's a painter, poet, publisher, photographer and musician. He's also a movie star who prefers to live in the bohemian stretch of Venice Beach over the gated mansions of Beverly Hills.

Not surprisingly, he was the Oscar-nominated actor (Eastern Promises) whose campaign was conspicuous by its absence last winter. Although he did attend the Academy Awards ceremony to honour, he says, those who worked so hard helping him play his Russian mob boss in the film.

Born in Manhattan to a Danish father and an American artist mother, the 49-year-old grew up gypsy-like, wandering the globe, landing in, among other places, Argentina, Venezuela, Denmark and then back in the United States.

So how does that qualify Mortensen for the Ed Harris-directed western Appaloosa opening Friday? Well, it doesn't, necessarily.

Although Mortensen is an expert horseback rider - thanks to a stint on his father's ranch in Argentina - which he proved as the lead in the 2004 movie Hidalgo and more famously before that as Aragorn in the Lord of the Rings trilogy.

Rider or not, the truth is Mortensen gave Harris his word that he would co-star in the oater when they worked together on A History of Violence. And that was that.

"I have great respect for Viggo as an actor and as a human being," says Harris who, as the co-lead, co-writer, director and producer, was the driving force behind Appaloosa.

"He's a really decent guy and great on the set, treating everybody respectfully," adds Harris. "And I just thought he would be perfect, so perfect that I'm not sure I would have made the movie without him."

It turns out both are suited for their parts. Based on the Robert B. Parker novel, the film features Harris and Mortensen as stoic lawmen confronting a corrupt rancher (Jeremy Irons). They end up at odds with each other as they compete for the affections of a manipulative widow (Renée Zellweger).

In fact, Mortensen and Harris have many things in common, especially their acting approach, which is clearly evident in the intense scenes that anchor Appaloosa.

"I liked the sparseness of the film and how well-written the language is," Mortensen says. "It's pretty curt, pretty direct, but there is a polite sensibility that is mostly gone now."

Certainly, his Appaloosa part is another in a continuing series of warrior roles, whether they be hero or villain. But he's not too worried about the potential for typecasting.

"I think maybe it's whatever people see," he says. "When I started my career, I could never play a guy who was either bad or dangerous."

You might recall that Mortensen made his movie debut as Harrison Ford's inquisitive and friendly Amish sidekick in 1984's Witness. Perhaps less noteworthy is his crazy cousin part in 1990's Leatherface: The Texas Chainsaw Massacre.

Mostly, he paid his dues in the 1990s as journeyman performer in A Perfect Murder as the conniving boyfriend opposite Gwyneth Paltrow, and as the tough Navy SEALS commander in Demi Moore's G.I. Jane.

The Lord of the Rings series changed his B-list status to A in Hollywood, but not his attitude about what he does for a living.

"You get out of your clothes and you get to be a whole other thing, with another world to live in," Mortensen says. "That's part of the fun of acting, and I still like that part a lot."