That's because McCarthy didn't want a big name to play Walter, someone who would have to come down from his stardom to seem pedestrian -- à la, say, Jack Nicholson in "About Schmidt."

Jenkins admits to being nervous when the cameras began to roll. It was, for a veteran who has done the giants onstage -- O'Neill, Mamet -- a new experience. The pressure had been on Charlize Theron in "North Country" (where Jenkins played her working-class father). It was on Billy Bob Thornton in the Coen Brothers' noir-ish "The Man Who Wasn't There."

"I think 10 years ago I would have been a little more [nervous], but, yes, I was," Jenkins said evenly. "I understood the responsibility. But I also was really excited to do it. I think I got nervous after the first couple of days. Then you realize, first of all, [McCarthy] wrote it for me. And if I can't make it work and he wrote it for me, then I'm really screwed."

He did not want to know everything the audience would never be told about Walter. In fact, it was what drew him to the project: its lack of exposition.

"It's almost like a novel going on in there," he said of the character's inner life. "I loved the fact that when I read it you don't know what he's thinking."

This rich inscrutability is a recurring theme in the parts Jenkins has nailed. One of the more memorable episodes of "Six Feet Under," called "The Room," had Nate (Peter Krause) discovering that his late father had bartered his mortuary services for the use of a spare room above an Indian restaurant, suggesting to the son that his father led some counter-life.

"What I loved about him in 'Six Feet,' " Alan Ball, the show's creator, said by phone, "is there's this genuine decency that he has, but you get the sense that there's a lot of serious complexity beneath that surface."

'Light bulb went on'

JENKINS traces his maturation as an actor to work he did decades ago with Harold Guskin, the New York acting coach who more recently worked with James Gandolfini during "The Sopranos."

Guskin wrote the book "How to Stop Acting," a title that speaks to the unadorned realism Jenkins brings. He discovered Guskin in Bloomington, Ind., teaching out of his basement; Jenkins, who is from DeKalb, Ill., and who later attended Illinois Wesleyan University, was at the time in a graduate theater company at Indiana University.

"He was the first one that the little light bulb went on," Jenkins said of Guskin. "He kind of says, 'You're who you are, who are you trying to kid?' And you say, 'But I'm not interesting enough.' He was kind of the trigger for me."

Jenkins has lived outside Providence for more than 30 years. Only once did he move -- a 10-month stay in Los Angeles, in 1975, when Jenkins started to worry about money after his first child was born. He lived over a carport on Sunset and Crescent Heights boulevards and paid $35 to audition for film and TV parts.

"Look at me," he said, asked if he had to age into movie roles. "What was I going to play when I was 30?"

One agent told him to think "hit man" parts.

"I came home, and I said to my wife, 'You know, we're going to have to find a way to do this here. 'Cause this is what it's gonna be.' "

The older he got, though, the more he worked. And the path that he eventually found, this longer, less predictable road, has left him saying today: "Yeah, Hollywood's pretty cool, actually."

paul.brownfield@latimes.com