You may not think you know Caroll Spinney. But you do.

The face may not be familiar and the name may not ring any bells. But you've seen his work and you've heard his voice. And the character he has played for the past 20 years probably ranks among television's most memorable and enduring.There's Archie Bunker, Lucy Ricardo, Ralph Kramden - and Big Bird. And Spinney is the man inside the Bird.

"One day I was climbing out of the costume and one of the little children on the set happened to see me," Spinney recalled during an interview in Los Angeles recently. "I heard him yell to his mother, `Does Big Bird know there's a man in there?' "

Big Bird knows, because Spinney has been behind the Bird's beak ever since Sesame Street first started entertaining and teaching pre-schoolers on public television in 1968. Only back then Big Bird was different.

"He was originally an incidental character who would be sort of a Goofy to Kermit the Frog's Mickey Mouse," Spinney said with the soft, gentle speaking voice that is his when he's not inside Big Bird's bright yellow feathers. "Then we realized that Big Bird isn't the village idiot - he's a child, with a wide-eyed view of the world. For a long time we played him at age 4. Now we see him as 61/2 - and there he stays."

A trained puppeteer whom Muppet creator Jim Henson discovered doing Punch and Judy shows, Spinney has become an important part of "Sesame Street's" dedicated and talented collection of performers. In addition to Big Bird, Spinney is also the heart and soul of Oscar the Grouch, the cantankerous garbage can-dweller who was created to show that people can have a different point of view and still be accepted.

But it's The Bird who has provided Spinney with the most fun - and the greatest challenge. The costume is really a huge puppet with a beak, head and eyes that must be worked. Spinney has to support the heavy head with one hand and work the various controls with another while he says his lines. He uses a tiny TV set inside to see how his "acting" is coming across. So strenuous is all of this that the puppeteer can rarely remain in the costume for more than 10 minutes without a break.

But he isn't complaining. "I genuinely, really do enjoy children," Spinney said, "and I realize that they love Big Bird and want to be his friend. I've tried to respect that feeling. When I get inside that costume I am Big Bird. I won't speak except in the Bird's voice, and I won't be photographed in partial costume - even though I've been chased by photographers trying to get a shot of me wearing just the bird feet. I don't want to take away the fantasy."

Even if that means going through life largely unrecognized despite being one of television's biggest stars.