Gary Coleman is 10 years old and 43 inches tall and the star, with Conrad Bain, of NBC's new comedy series "Different Strokes." But do not call Coleman a star to his face, or you'll get yours.

"I don't like being 'star'," he says with his arms folded in front of him. "Star star star. That's what my relatives have started to call me - 'Hey, star!' That's what my Uncle Henry calls me. Well, I have a name like everybody else."

Gary Coleman is not like everybody else, however, nor is he much like any other child. He's not only talented, bright and faster than a speeding bullet, he's also one of the most unflappable celebrities in the business. To say he takes his career is stride is putting it mildly; "I just get up there and do it and get it over with," he says testily, his glasses slipping down his nose as he eats a piece of carrot cake in an office at Tandem Productions.

There doesn't seem to be anything that can scare this kid, and that includes appearing on "The Tonight Show Starring Johnny Carson," as he did a couple of weeks ago.

Gary looks back on this as a triumph.

"I think I just KILLED him," he says. "I killed a great actor."

To Carson: "I had it out with my mom today. She wanted me to wear my best clothes to this show, and I said, 'WHY?'"

Carson did his standard stricken double-take into the camera.

Carson stumbled over the title of Gary's show. "Have you forgotten the name already?" the kid scolded.

Carson: "Do you know about the birds and the bees?"

Coleman: "No I don't want to know, either."

Gary said he wanted to be "just my mellow, comedy-actor self," and as Carson started to interrupt him, he said, "I know what you're going to say - It's time for a commercial.'"

"What night are you available for guest-host?" Johnny asked.

The Carson staff called Tandem during Gary's lunch to invite him back; Johnny will face him again in December.

Our interview, however, had begun on a shaky note. Gary marched in with his mother, Sue, and announced, "I'm SUPPOSED to be on my lunch hour.

This isn't temperament; it's a kid exercising his prerogative to remain a kid while all around him people are trying to make him an adult. Gary Coleman has become a pawn in the national network money game. NBC president Fred Silverman personally chose him to star in "Diff'rent Strokes and ordered an advertising campaign built around him. Then Silverman's ex-boss, ABC-TV president Frederick S. Pierce, tried to sabotage "Strokes" by moving "Happy Days" opposite it -- over the protest of "Happy Days" producer Garry Marshall -- the week "Strokes" premiered.

It hurt, but the next week, "Strokes" bounced back, with better ratings than "Battlestar Galactica," which happens to be Gary's favorite show. Also he says, "I think 'Happy Days' is dumb."

Pierce was eager to shoot down what Silverman had called "the first Fred Silverman show" since he took over NBC Coleman might have jointed the ABC stable if Silverman had reassined there, because there was interest in the youngster back then.

In a recent TV "awareness" survey commissioned by NBC Gary Coleman came in first, outranking such venerables as John Wayne and Walter Cronkite in terms of pure lovability. Now millions of dollars and more than one career are resting on his tiny-tot shoulders.

Using cute kiddies to bolster TV ratings - and putting grown-up sayings in the mouths of babes - is nothing new, but the standard child has been the squeaky clean, tow-headed blue-eyed little darling. Gary Coleman adds an impudent new wrinkle to the adorable syndrome; on and off the screen, he belongs to a new generation of take-charge children. "He owns the studio," says a Tandem publicist. "The kid runs the place. We just do what he tells us."

"Hey - what's this hair doing in my sandwich?" growls Gary from the other room.

As an actor, his line readings are instinctively perfect and punctuated with extravagant gesticulations that are all the funnier for coming from such a small, pudgy source. "I study the script frequently," Gary notes, "and I change lines now and then" to make them more natural.

Shirley Temple in her prime would never have been able to keep up with this; she devoted her child life to pleasing adults, not telling them what's what. Gary refuses to be pushed around or to be overwhelmed by such prosaic adult concepts as being the star of a hit TV series.

For his part, Gary would just as soon be home playing with his electric trains in his birthplace, Zion, Ill. -- described by him as "just a little township, and then a town, and then a city, all molded up into a little 4,400-acre site."

He will spend Thanksgiving Day there with his mother and his father, Willie. He is their only child, and they almost lost him.

Born with a chronic kidney ailment, Gary was in and out of hospitals until the age of 5, when he underwent a successful kidney transplant.

"Thank God, he's been all right ever since," his mother says.

"Knockin' like a pin!" Gary confirms. "Each time I went into the hospital, I went in smiling. I said, 'So what, so what? An operation is an operation. This is just a kidney transplant. I ain't gonna DIE from it,'"

"I'm glad you knew that" says Mrs. Coleman. "Cause Daddy and I weren't so sure."

Specially when they had to pay for it after we got through," Gary says, laughting. "I'm still payin' for that operation now!"

"He's not a person who will feel sorry for himself or let things bother him," his mother says. "He was going to be all right and he knew that, and he helped his father and me accept it a lot better."

Gary looks up from his carrot cake. "Up, up and away!" he says.

"Diff'rent Strokes" is about a white millionaire who adopts two black kids when their mother -- his former housekeeper -- dies. Gary has no illusions about this art. But it is funny?"

"Nyaaaaa," he says. "In some shows, yes. But 'Goodbye Dolly,' the one we're working on now, I think is going to be a FLOP. I don't particularly like that show. All the dumb lines they threw into it! It's about a doll that I sleep with -- who wants to see that? Why can't be something important, like it's always been? A doll! Who wants to see that baloney?"

Do studio audiences always laugh at the right time? "No, they're as dumb as we are."

Does he like signing autographs? "No. I remember one night when I had to sign at least 300 of them. I got writer's cramp! My hand was like THIS." He scrunches his hand into a gnarl.

That, however, was a big night in Gary's professional life, which began at the age of 6. One year ago he won a CLIO award for best commercial of the year, honoring a spot he had done for the Harris Bank in Chicago. The ceremony was held at the Playboy Towers, which gave Gary a unique opportunity for research.

"I had to find the bunny tail," he recalls, smiling with self-satisfaction. "There were lots of them running around. They were so conscious about their tails, though. Every time I tried to look behind them, they would always turns around! I turned around the other way and said, '-Ah-HA! They do have the little bunny tails!"

He doesn't expect to remain an actor all his life. "Any number of things would be good enough for me. Easy jobs.Ohhh, a paper route, something like that." He knows his ratings are good -- "we're gettin' up there" -- and thinks that if the show clicks, "a good three years would be enough" for him.

Besides "Battlestar Galactica," he also likes to watch the news on TV. "I like news. I watch it every chance I get -- to see who got killed this time, who got in an accident, and if the mud slipped off the hill yet."

He says he has no heroes, not even in, say, the White House. "Aw, Washington -- that ain't no place. The president? No, you know, I don't like the president, or the Senate. Those are the people who are makin' life IM-possible!"

Gary wants to stay "just my same old self," he says, and his mother says, "He's really a pretty good kid." Before zooming out the door in his railroad hat and heading back to the soundstage for rehearsal, he is told that he will have to give many more interviews like this one in the weeks to come.

"Yeah, I know, he says. "Isn't that TERRIBLE?"

And -- flash -- he is gone.