He’s got one of the most famous voices in showbiz — a low, whispered growl that can be played for menace, or laughs. But as anybody who has caught Alec Baldwin on “30 Rock,” “Saturday Night Live” or even “Inside the Actor’s Studio” can attest, he’s more than happy to hide that. A gifted mimic, he’s taken down everybody from Richard Nixon to his “30 Rock” co-star Tracy Morgan with his killer impressions.

But he’s rarely asked to be “just a voice” in a movie or TV show. And when he was asked — for the new DreamWorks animated holiday comedy “Rise of the Guardians” — he knew he wasn’t going to play it straight.

“Jeffrey Katzenberg called and said he wanted me to play this — How can I put this in politically correct terms? –a complicated, competitive Santa Claus,” Baldwin recalls “He’s macho.They had suggested Santa be someone from the Siberian wilderness.

“A lot of times, your initial take on what they want is the best idea. You can think these things to death. I’ve done plays and films where we’d have dialect coaches come in and they would teach you how to nail it, get it truly authentic. But sometimes, that makes the character hard for the audience to understand. So they ask you to homogenize it so people can understand it. I’ve done plays where they say, ‘Give us LESS. We don’t need precise, we need just enough.’

“So I fell back on my stock ‘Rocky & Bulwinkle’ Boris Badonov accent here. Saturday morning cartoon Russian — that’s what I went for. I think that’s still funny”

Baldwin knows funny. Ask Jerry Seinfeld. When the veteran comic was casting people to pick up in vintage cars for comic riff-offs in his web series, “Comedians in Cars Getting Coffee,” he called on Baldwin.Baldwin protests that “I’ve imitated a comic for a while. But that’s about it. Jerry, like (“30 Rock” creator and star) Tina Fey and most of the people on ’30 Rock’ and all of the people on ‘Saturday Night Live’ write their own material. The ‘comic’ label for me implies people who write funny things that they then perform. I don’t write. I’m lucky enough to perform the lines that other people gave me.”

A two-time Emmy and three-time Golden Globe winner for his turn as a smooth, cunning and yet politically and comically tone-deaf exec on “30 Rock,” Baldwin was singled out by the New York Times Magazine as one of “Eight Actors Who Turn Television into Art.” But those days are ending. “30 Rock” will end its run, despite Baldwin’s efforts (he says he offered to cut his salary) to keep it on the air.

“At first, I was terrified of the show,” he says. “I had guested on comedies, but to do this with all those folks was very daunting. These people were all very successful improv comedy or stand-up comedy performers. Jane Krakowski and I were the only pure actors who came into that world of comedy people.

“Then, when the show did well and we got a lot of awards, ratings and recognition, we seemed to coast on that high for two or three years. That felt good.

“Then, it got old for me. I realized I couldn’t stand doing the same thing any more. I went into the sixth year thinking ‘I will never do this guy again.’ But you get married (this past spring), and you realize how much you love the routine, the hours. The lifestyle is very atractive and I thought, ‘I could do this two more years, sure.’ That lifestyle is a real selling point.

But now that it’s over and it’s going to end, I’ve come around to ‘That’s a good thing.’ I am excited and nervous about going back to the sort of career I used to have. Dramatic parts, and the fact that I really don’t know where I’m going to be six months from now. That’s what life was like before ’30 Rock.’ “

And the onetime narrator of TV’s “Thomas the Tank Engine” is happy to be doing a children’s animated film. “Rise of the Guardians,” he says, may be the best way for an actor working today to guarantee his immortality.

“Kids’ movies go in five year generations. You’ve got the ‘Little Mermaid’ generation, the ‘Pocahontas’ generation, kids who came up on ‘Shrek’ and then kids who were the first to see ‘Madagascar.’ A couple of years go by and there’s a whole new crop of kids comes along, and they’re going to see these movies not in theaters, but at home on DVD.

So that’s what you remember when Jeffrey Katzenberg and Dreamworks calls. Every good movie like this has a chance to access generation after generation of kids. There’s nothing else in film that can make that claim.”