ON TUESDAY night, on Wednesday night and again tonight, from 10 to 11, NBC presents "Live . . . and in Person," a variety show featuring such glitzy talent as Neil Diamond, Dolly Parton, Kenny Rogers, Joan Rivers, Lily Tomlin, Mac Davis, Barry Manilow, Alan King, Liberace, Men at Work and, of course, your host, the ever-popular Sandy Gallin.

Yes, Sandy Gallin, who introduced himself to a national audience that didn't know him from a bushel of wheat, and told them how he never even imagined he'd be on stage doing this, introducing big-name acts on his own show, how it was a dream come true for him, how he was so pleased to have his good friends like Joan Rivers and Dolly Parton and Neil Diamond on stage with him, live, and in person, in a show that Sandy Gallin himself says, quite justifiably, "was presented spectacularly."

Time out.

Sandy Who?

America wants to know.

Following in the footsteps of Mr. Excitement, Ed Sullivan (which is not exactly like walking a tightrope over Niagara Falls), Sandy Gallin strode onto the stage live, in person and in a tuxedo no less. Looking out at the thousands in the audience and knowing there were millions more watching at home, Sandy Gallin could palpably feel what Americans were thinking. "They were thinking," Sandy Gallin said yesterday via the marvel of telephonic communication, " 'Who the hell is this guy? And where's Dolly Parton?' "

Undeterred, Sandy Gallin did what could only be described as his unique thing. And what a thing it truly was. His glittering teeth glittered. His boyish smile smiled boyishly. His infectious enthusiasm infected all of us. He introduced big name acts, waving them on and off stage like a Rototiller. Tipping his hat to the late, great Sullivan, he even introduced celebrities from the audience, like clothes designer Calvin Klein and clothes wearer Miss America, in what could only be described as his unique style.

He did it all. And, not one to cop Sullivan's nonpareil ambiance, Sandy Gallin did it without appearing somnambulant. What a debut! What a triumph! Ladies and gentlemen, a star is born! While some emcees are content merely to introduce big-name acts with a perfunctory point and a wave, Sandy Gallin got involved. He immersed himself totally, yet unoffensively, in the moment, in what could only be described as his unique way.

And why Sandy Gallin? "Because I felt," Sandy Gallin said, "you could not have a star host a variety show. Stars are too conscious of their image. This one won't appear with that one; that one won't appear with this one. You need someone who could get the acts on stage and get out of the way, someone with absolutely no credentials as a performer at all. And I thought to myself--'Why not me?' I had the credibility with the people in this town. I went to NBC and told them this, and they looked at me like I was crazy. Then they said--'Why not?' "

Sandy Gallin, we are told by publicist Len Rosen, "has never been on television before; he's not a performer." (No kidding.) Yet clearly, as was evident to anyone who watched the show Tuesday night, not since Sullivan has a man seemed so right introducing big-name acts and even big-game acts like the Berosini Orangutans. To those who say that Sandy Gallin displayed no discernible talent, I say, where is it written that you have to play King Lear in order to say, "Ladies and gentlemen, Cher." Did Sullivan have talent? If he did, he surely disguised it. And who would dispute that if Sandy Gallin has even a shred of talent--other than, as he says, "a gift to know talented people"--he disguised it, too? He disguised it magnificently; in fact, he obliterated that sucker.

And to those of you who say that Sandy Gallin is nobody, to those of you who say a moose could emcee a variety show, to those of you who say Sandy Gallin only got the gig because his production company put the shows together, I say, stop niggling, this kid is a natural. Anyway, this is America. You've got a choice. You want urbane, call John Updike, he's in the book.

Maestro, if you will, a little biography music: Eligible bachelor Sandy Gallin was born 43 years ago in Brooklyn (Let's hear it for Brooklyn!) and raised on Long Island. He has told people that after graduating from Boston College he "wanted to be a singer or an actor, but those were the days of the pretty boys like Ricky Nelson and Frankie Avalon, and I didn't feel I was good-looking enough to compete with them." So where did Sandy's vision take him? Let's let him tell it: "Because I loved show business so much, I went to work in the mail room of GAC, a New York talent agency." (Let's hear it for the mail room!)

From there, Gallin rapidly rose to secretary to an agent who handled "The Ed Sullivan Show." (Let's hear it for irony!) Then he went on to be a junior agent, then head of the agency's variety department, where he became involved with such shows as "What's My Line?," "To Tell the Truth" and "I've Got a Secret"--the premises of which could serve as metaphors for what he's been doing this week.

Moving out to Los Angeles, where palm trees grow and rents are low (Neil Diamond, 1971), Gallin opened a talent agency, and, with his partner, Raymond Katz, formed Katz-Gallin Productions, which packaged and executive-produced these three specials. Gallin, who, in the words of Len Rosen, "is one of the most important personal managers in show business" (Let's hear it for important personal managers; they're beautiful, baby, beautiful!), manages some important persons like Joan Rivers, Mac Davis, Florence Henderson, Dolly Parton and Debbie Allen. (Let's hear it for leverage!) And Sandy, who is nobody's dope, came up with the concept of "a 1983 version of 'The Ed Sullivan Show,' " got his acts together, and sold the whole kit and kaboodle to Brandon Tartikoff, president of NBC Entertainment.

That is how Sandy Gallin came to host these shows with what could only be described as his unique personality. As Tartikoff says, "Nobody loves talent and loves to present talent more than Sandy Gallin. While he has never appeared in front of the cameras before, he is a showman extraordinaire." The rest, as they say, is show business history. (And please, one more time, let's hear it for history!)

The burning question, of course, is what's next for Sandy Gallin? What rivers to cross? What mountains to climb? What filets to fish? "I'm not positive yet. Let's see how they respond to these shows first," Sandy Gallin said in what could only be described as his unique voice.