Now, he is up for an Oscar for his performance as Senator Ralph Owen Brewster, Howard Hughes' nemesis in "The Aviator."
Alda can't seem to wipe the smile from his face since his nomination.
"I love it," Alda tells The Early Show co-anchor Harry Smith. "People coming up to me on the street, telling me, 'Congratulations.' And they're very impressed, you know. It's like a whole new category I'm in now. I really like that.
"Yes," he exclaims enthusiastically. "You're a good actor! It feels pretty good."
He was born Alfonso D'Abrutzo in New York in 1936.
His father's screen name was Robert Alda, also an actor, who spent his life on the stage and in movies.
Robert Alda's first picture was a giant hit. He played George Gershwin in the film biography called "Rhapsody In Blue." Then he played Sky Masterson in the original Broadway production of "Guys And Dolls." After that, Alana Alda says with a laugh, his father never made money again.
Young Alan spent a lot of time backstage, watching his dad work in burlesque houses as part of a comedy team.
When it came time for college, his father was thinking medicine. But Alan found work on Broadway; and did television and movies, when he could, winning favorable reviews and a Tony nomination.
And then came "M*A*S*H."
Says Alda, "And I called Arlene (his wife) and said, 'You know, this is the best pilot I've ever seen. Too bad I can't do it because it's gonna be shot in California and we live in New Jersey. And our kids are just going to high school now. Because you know,' I said, 'this thing could run a year!' "
"MASH" ran for 11 seasons, becoming one of the best-loved shows in television history. And Alan Alda became one of Hollywood's best-loved actors.
For many women, Alda seemed the perfect man, a witty actor who embraced feminism.
How sweetly ironic that this champion of liberal causes plays not one, but two Republican senators.
On "The West Wing," he's Sen. Arnold Vinick of California, making his run for the presidency.
Alda notes, "I feel bad when people ask me - and I get asked this in most interviews about 'West Wing' - people say, 'Well, if you become president, and you 're a Republican, you're gonna have to say all these Republican things. Will you be able to do that?' And my answer is: 'Have we so convinced ourselves that we're either red or blue, and we can't listen to one another?' "
In "The Aviator," it's Sen. Ralph Owen Brewster, the role that brought him his first Oscar nomination. Asked if he would like to win, Alda says, "I don't think there's any chance that I'll win. Of course, I'd like to win. Of course, I would. Are you crazy? I'm not gonna send Jean Littlefeather, or whatever her name was - that woman who picked it up for Brando." (Her name was Sacheen Littlefeather.)
So if he wins, don't expect to hear: "Alan Alda will not be accepting his Academy Award."
Laughing, Alda says, "Yeah, come on."