If things have gone as Matt Groening originally planned, every Sunday night at eight, America would be tuned in to a oneeared rabbit and ugly gay twins in fez hats. If that wouldn’t make you switch over to “Big Brother 8,” nothing would.

“The Simpsons” began inauspiciously. In the mid-’80s, Groening was a struggling underground cartoonist,

publishing a strip called “Life in Hell” in the L.A. Weekly. It featured an odd cast of characters, including a depressed rabbit, his illegitimate, one-eared son and twins Akbar and Jeff.

James L. Brooks, a renowned sitcom and movie director, approached Groening about turning “Life is Hell” into a series of animated shorts to be featured on “The Tracey Ullman Show.” Before the meeting, however, Groening had second thoughts about selling his creation and decided to pitch Brooks (and the Fox network)

something new.

As the artist sat outside Brooks’ office, he quickly dashed off a crude rendering of a dysfunctional family based on his own. And so from a doodle was born the most successful sitcom in TV history.

As casting began, Brooks turned to Dan Castellaneta (Homer) and Julie Kavner (Marge) – both currently

working on “Ullman.” The roles of Lisa and Bart, however, had to be filled by outsiders.

“I had been working for about six years and was on eight Saturday morning cartoon shows,” says Nancy Cartwright. “My agent calls up and says there’s this little audition for this interstitial. I didn’t even know what that was. It’s like mini-entertainment wrapped around a commercial. So it’s not even a show. It’s less than a show. I said all right, but I was a bit nonplussed by the whole thing.”

Cartwright originally came in to read for the part of Lisa, but once she saw the description of Bart (“10 years old, oldest child, a school-hating underachiever and proud of it”), she told Groening she’d rather be the boy.

“Who wouldn’t want to do something like that?” she says.

Cartwright was hired on the spot, and Yeardley Smith, another veteran voice actor, took the role of Lisa.

“The Simpsons” premiered in 1987 on “Ullman,” but hardly felt like a the seed of a megasuccessful franchise. Despite the middling popularity of the shorts, suits at the then-ailing Fox network liked their edgy humor, and in 1989 reluctantly agreed to give the animated family its own half-hour series.

“[Show runner] Sam Simon was looking for writers, and I was one of the first hired. I actually took the job because it was two days a week and no one else wanted it,” says Al Jean. “I thought it might be a hit, then peter out quickly. I’d worked on the show ‘ALF,’ which was a huge hit, but only lasted four years. That was sort of my fear.”

“Simpsons Roasting on an Open Fire” premiered in December of 1989, and the show’s anti-family values quickly won over critics and audiences numbed by years of traditional sitcoms. USA Today asked, “Why would anyone want to go back to ‘Growing Pains’?”

“Matt Groening grew up watching shows in the ’50s and ’60s with these perfect families, and that’s not really what it’s like,” Cartwright says. “For him to come up with this concept to create a dysfunctional family that’s more real than what was considered real, it was brilliant.”

“When I saw the first episode completed, I thought this is the best thing I’ve ever been involved with,” Jean recalls. “It was funny, but at the end of that episode, Homer goes to the dog track, and he brings home this little dog named Santa’s Little Helper, and the family is so happy to get the dog that Christmas is saved. It was the sweetest, most emotionally resonant thing I’d worked on.”

By the end of the first season – which included episodes about Bart cutting off the head of a Jebediah Springfield statue, getting sent to France for misbehaving and clearing Krusty the Clown of robbery – the show was a certified hit, becoming the first Fox series to crack the Top 10.

It was also a pop-culture phenomenon. Ironically, the show that had been born out of a reluctance to sell out had now become a franchise that launched a huge trade in clothes, toys and air fresheners. Merchandise with the catchphrase-friendly Bart was especially popular. Emblazoned with “Don’t have a cow, man” or “Eat my shorts,” show T-shirts were selling at the rate of a million each day.

“We were pinching ourselves,” Jean says. “You could open the paper and say, ‘I’m going to find an allusion to “The Simpsons,”‘ and you could. You would walk down the street and you’d hear people talking about it.”

“I took it in stride,” Cartwright says. “I’m not Bart. Thank God I don’t have nine spikes on the top of my head and sound like that all the time. That would be weird.”

To this day, cast members and guest stars get bombarded everywhere they go with rabid fans wanting DVDs, figurines and talking Bart dolls signed.

“You’ll go to a restaurant and you’ll come out and there will be a few people waiting there with pictures and toys,” says frequent guest star Albert Brooks. “I thought, ‘Gee, you’ve carried around this toy for a long time.’

They obviously have to have a big trunk.”

But in those early days, not everyone was pleased by the show’s success. It was often criticized for being crude, anti-family and promoting delinquency. Then-President Bush even took a swing in 1992, saying Americans needed to be more like the Waltons, less like the Simpsons.

“There were schools that banned Bart Simpson T-shirts, including my own daughter’s. The school still asks me for money, which I find ironic,” Jean says.

“Myself, I just went, ‘That’s part of the p.r. machine.’ You can’t please all the people all the time,” Cartwright says. “The writers can’t listen to that. They have to write for themselves and what they think is funny.”

By seasons four and five, many of the original writers began to leave to pursue other projects, including Sam Simon, who’d helped create the show but reportedly had a bitter falling out with Groening.

Another of the writers to bolt was Conan O’Brien, who’d been with the show for two seasons and wrote what’s considered one of the all-time classics, “Marge vs. the Monorail.”

“Ironically, my first day turned out to be his last,” says writer Mike Scully. “We had literally just been introduced to each other across a table, shook hands, and somebody tapped him on the shoulder and said he had a phone call. He left the room and never came back. That afternoon, we heard he’d been given the latenight show on NBC.”

“I took over and started season five. It was a tumultuous time,” says writer David Mirkin. “There was

a lot of scrutiny on the show. We wanted to make it more emotional and bigger in scope. It was a time

for the show to grow. It was the first time we started to travel freely to other countries. We went to India

with Apu. We went to Australia.”

During these years, the show also began to shift its focus to the man who would eventually be voted TV Guide’s second greatest cartoon character of all time: Homer Simpson. The season included much-loved episodes in which Homer is tapped to become an astronaut (“Deep Space Homer”) and one in which Homer

teaches couples counseling, only to tick off Marge by spilling personal details (“Secrets of a Successful

Marriage”).

“We started writing more Homer stories, I think because we’re more like Homer than Bart. It was just easier to think of Homer ideas,” Jean says.

“Bart, to write him accurately as a child, he can only have so much depth at a certain age,” Mirkin says. “With Homer, we try to explore all levels of adulthood- or arrested childhood. There are just more places to go.”

“Writing Homer properly is the trick. He’s our main rock of the whole series,” Mirkin says. “Homer’s

IQ is fairly flexible. He won’t necessarily understand how to open a door at some point, but he can name the Supreme Court justices. Finding that balance is key to making the show work and making it surprising and making it believable and emotionally grounded.”

“Homer is endearing because we see our imperfections in him,” says Brooklyn’s Steven Keslowitz, author of “The World According to the Simpsons.” “Homer is like looking in a carnival funhouse mirror. We recognize some parts, but he’s sort of what we don’t want to become.”

The show through the seasons also began to create a rich and sprawling supporting cast, which has now grown to at least 60 speaking roles, including Comic Book Guy, Disco Stu, Cletus the slack-jawed yokel and the rest.

To many fans, seasons four through eight represent a “Simpsons” Golden Age. The characters were fully developed and the humor got wonderfully bizarre, such as “In Marge We Trust,” in which Homer discovers his face on a box of Mr. Sparkle detergent in Japan, or “The Mysterious Voyage of Homer,” where he hallucinates after eating hot peppers at a chili cook-off.

“It’s not so much that there’s a set golden age, but there was a time that the show was new and different and every story possibility was open to you,” Scully says. “It can’t stay that way forever. Some repetition will set in.”

The writers admit that through the years, it has become increasingly difficult to dream up new plotlines

for Springfield’s famous family. But despite some longtime fans griping about the series waning in recent years, Jean – who currently runs the show – points out that “The Simpsons” won the most awards in its history last season.

“I like that they haven’t forgotten from whence they came,” says Joe Mantegna, who voices mobster Fat Tony. “That’s what keeps the quality of the show as high as it always was. Usually when you run this many years, it gets worn around the edges.”

Regardless of whether “The Simpsons” has lost a step or not, one day it will inevitably end. And that end could come as soon as next season. The cast has not yet inked a contract to continue, and after an ugly battle in 2004 in which Castellaneta and the rest held out for $360,000 an episode, the chances of agreeing to terms

again are hardly a sure thing.

But how will “The Simpsons” go out? Surely not with a jolt of Journey and an abrupt cut to black.

“We used to periodically talk about a finale episode,” Scully says. “It was kind of an assignment that no one ever completed. I think ‘Everybody Loves Raymond’ went off in a way that shows should go off, which is that life is going to continue on for these characters, we just won’t get to see it.”

“Somebody asked me what will you do when the show ends? It’ll be like your best friend has moved away,” says Yeardley Smith. “I think the transition may be difficult for me.”

When it does bow out, it will leave as one of the most influential shows in history. It was free to take on controversial issues (gay marriage in season 16, the Iraq war last year) and push limits, in large part because Brooks had negotiated a deal forbidding Fox execs from giving notes.

“You don’t have to get network approval for every story. If we did, the show would have been off the air around season four,” Scully says.

“Families put their children in front of it because it’s animated, but they don’t realize it’s beyond any kind of satire,” says director John Waters, who played a gay antiques dealer. “It does what Mad magazine did for me. It radicalized me. I think ‘The Simpsons’ is the first secret things kids see when they realize they don’t have

to listen to everything people are telling them. It sows the seeds of rebellion in the best kind of way.”

“People get it wrong when they say it’s a family that works,” Mirkin says. “It doesn’t work. These are not good parents, they’re not doing a good job. Marge is in the relationship with Homer for all the wrong reasons. It’s a mess.

“Things don’t get fixed up after 22 minutes in real life, and the point of the show is, that’s the way it is,”

Mirkin adds. “Things get screwed up and they don’t work out properly, but that’s OK. That’s the way life

is. It is survivable, it is enjoyable, it is funny. Embrace that.”