From early on, Mr. Duvall enjoyed the life of a supporting actor. “Somebody once said that the best life in the world is the life of a second leading man,” Mr. Duvall told The Times. “You travel, you get a per diem, and you’ve probably got a better part anyway. And you don’t have the weight of the entire movie on your shoulders.”

Even as a boy, in a Navy family that moved around the country, he had an ear for people’s speech patterns and an eye for their mannerisms. “I hang around a guy’s memories,” he once said. Insights that he gleaned were routinely tucked away in his head for potential future use.