You know , of course, what Gahan Wilson looks like, especially if you've never seen him. You've known ever since the first Gahan Wilson cartoon started gnawing on the edges of your psyche -- terrible slime-sac monsters lurking over children in cribs; a chimney cleaner standing over a skeleton in a Santa Claus suit and saying: "Well, we found out what's been clogging your chimney since last December, Miss Emmy."

"He'd have Uriah Heep kind of hands," says a young woman chosen at random (rather like a victim in a Cahan Wilson cartoon). "He'd have nervous lips, he'd keep pulling his lip over his teeth. He'd have flushed cheeks, maybe with burst capillaries . . . clean but untidy . . . might be obsessive . . ."

Build your own Gahan Wilson: it's like each of his cartoons is a kit for the imagination. Run-down shoes, pockets full of lint he rolls between his fingers . . .

"Wrong! Wrong on all counts!" cries Nancy Winters, the novelist who is Wilson's wife of nearly 13 years.

"Usually, they think I'm little, wrinkled and green," says Wilson himself, who in his late 40s is tall and sandy-haired with a haphazard moustache, a safari jacket and cowboy boots -- the patina of success. His cartoons have been appearing for more than 20 years in Playboy, The New Yorker, Esquire and The National Lampoon.

"Or they think I'm English and evil, a Doctor Moriarty. That's okay with me. In time, I'll probably turn into that."

For now, sitting on a hotel bed, drinking champagne at 11 a.m. and holding his feet up because the previous occupant left the tub running too long and soaked the carpeting, Wilson has nothing strange about him at all. Unless you count the interesting way in which his eyes roll somehow independently of his face, like those of a choleric cow.

For Wilson, monsters are everywhere, they are obvious, and they are only one logical step away from reality. He recalls two examples:

"There's one cartoon with a restauant way out in a desert with a gigantic sign flashing 'EAT.' Looking over the horizon is this huge monster. A guy in the restaurant is saying: "My God -- do you suppose it can read?"

Or the monster is within. One cartoon "shows a little girl looking at a tree growing along a sidewalk, a little tree with an iron protective fence around it. She's screaming, terrified.[Here Wilson tugs his lips back against his teeth and rolls is eyes.] Her mother says: 'Don't worry dear, it's just a tree.'"

He is a devotee of the writings of Carl Jung, who told us that there is no difference between the monsters within and the monsters without. Wilson likes seeing the world that way. He claims a very happy childhood as an only child in Chicago, says he was believed stillborn until the doctor plunged him into ice water and he revived. He studied at the Art Institute of Chicago, and began selling his macabre cartoons in the middle '50s.

Wilson has just published a collection of his cartoons about a small unnamed boy over whom tower the weirdness and hypocrisy of the adult world, It's called: "Nuts."

His wife, a fiercely kinetic blond, has just published a novel titled "Daddy." She has just been notified of a rave review from Eliot Fremont-Smith at the Village Voice. Hence the champagne at 11 a.m.

"One reviewer just hated it,hated it, but now . . . " she says.

Her notes on the new, good review lie on the table: ". . .the forbidden is the greatest literary challenge, and like Everest, incest is there to be mounted, as it were."

She dedicated the novel to "My Daddy -- Who Was Always the Ringmaster on the White Horse to Me."

"No, there was no incest between us, of course not, it's just taking a situation to its logical extreme."

Exactly, It's what she and wilson are good at -- perceiving the world as a collection of extremes, seeing it as children, in other words.

They are always together, they say. She goes on his publicity tours, he goes on hers. They answer questions and seem to work hard at turning life into instant legends, a set of tags: "We've lived in a tropical paradise, a Thoreauvian wilderness, country chic, and a small, livable city," they say, taking alternate phrases, then explaining that they're referring to Key West, the Berkshires, Kent (Conn.), before Bill Blass got there) and Boston.

"We're like the Bobbsey twins," says Wilson.

"I'd been married a million times, and Gahan was planning to be a lifelong bachelor. We'd been friends for years. Then it turned into more than that. He used to buckle me into the safety harness on his Triumph without ever touching me. Can you imagine how hard that is? Then one night we were walking into a party and he touched me with his horefinger and I thought, 'O my God . . .'"

They get up early now, in their apartment three doors from Richard Nixon's $750,000 townhouse on Manhattan's East 65th Street. They wish each other a good day at the office, then walk to work spaces on either side of the apartment. Then lunch, then work until 5.

"We have to force ourselves not to work. We'd go seven days a week," he says.

They also have a place in Connecticut. "Don't say exactly where -- last summer there was a pathological murderer hunting for us," says Winters.

The monsters proliferate, year by year

"Gahan says that he used to get his inspirations from Frankenstein but now he gets them from Walter Cronkite," Winters says. Wilson says yes, he said that to Walter Cronkite himself, one night at dinner.

"Things have changed," he says, "we have a totally irresponsible technology. It has run amok. The arrogance of it . . . like the experiments with life forms. They should be carried on, if at all, out in the desert with five rows of fence surrounding them. But they do it in Cambridge. God what pieces of things these scientists are walking around with on their tweeds."

Wilson rolls his head as he careens his whole face into a mad-scientist routine: "We could destroy all matter; Yes! Let's see if it works!"

Wilson already knows. He's cartooned it. Erect the technological triumph of a giant neon sign reading "EAT," and suddenly there's a monster slouching toward the restaurant to do just that.

There's no such thing as a joke, said Freud, but we keep laughing, and Wilson keeps worrying about the world in his fey rant:

"We're all in some totally insane way preparing to live in a spaceship. There's no other explanation for shopping malls and fast-food places -- limited, deprived environments where we just get by."

There is hope, however. It is in Transylvania. Wilson and Winters went there last year to research the Dracula legend.

"They have this strange blend of mysticism and ecology," says Wilson. "It was much better than I thought it would be. When we crossed over the Carpathian mountains we were on this road . . . well, they made the road in a tentative way, to see if the mountain would accept or reject it, and it was rejecting it."

"Landslides!" says Winters with equal delight.

Wilson says: "We came over the mountains in this incredible thunderstorm, bolts of lightning, thunder. Just as it was over, we saw this great big pale butterfly flopping toward us in the damp air. And the guide said: "I theenk Drah-koo-lah is taking the form of a giant butterfly!'"

And Wilson, mulling this memory, and perhaps the fact that he's spent his career fluttering back and forth in the same transaction, looks pleased.