In the peculiar, parallel world of American television comedy, ugly people generally serve one of three purposes. They can be nerds, they can be the Kramer-esque clown or they can be the ugly duckling, with swandom sure to follow. It hardly needs saying that they probably won’t be genuinely, mirror-crackingly repellent, or they wouldn’t get past the read-through. Just ugly-enough-for-purpose usually serves.

In Ugly Betty, the new hit American comedy that begins on Channel 4 this Friday, Betty Suarez (played by America Ferrara) breaks the mould. She starts ugly, and the set-up demands that ugly she must stay. Betty is hired as personal assistant to the newly installed editor-in-chief of Mode magazine, Daniel Meade, but it’s got nothing to do with her CV and everything to do with her train-track braces and wolfhound hair: Meade’s father Bradford (Alan Dale) owns the magazine, and he needs his bed-hopping son to concentrate on circulation figures rather than the figures of the Prada-clad floozies who make up most of Mode’s staff. So Betty gets the job by dint of being the worst-looking girl in the building.

With an average of 14 million viewers, Ugly Betty has been the only comedy success story in American TV this season, but if ever any new show can be called a safe Bet, ahem, this was it. The story that unfurls ropes together elements of several recent hits: the series is based on a hugely successful Colombian telenovela (a Spanish-language soap with a limited run), which has been adapted round the world. In all adaptations the winning premise remains — Betty may be ugly but she’s quickerwitted, kinder-hearted and more resourceful than all the sneering mannequins around her.

Much of the comedy pricks the pomposity of the fashion world — a seemingly bottomless gag pit that has sustained both Absolutely Fabulous and The Devil Wears Prada, and still provides plenty of grist to the mill in Ugly Betty. Finally there’s a Desperate Housewives-style mystery subplot. One of Mode’s former editors appears to be trying to bring down not just editor Daniel but the entire Meade empire.

The nub of the piece may be familiar but there are elements of Ugly Betty that are entirely new to television. It’s not just Betty’s penchant for ponchos or her dime-store specs that make her instantly abhorrent to her upper-class colleagues — she is a Latino living in Queens, which might as well be a different continent as far as the gilded Manhattanites are concerned.

American network television has yet to work out what to do with the country’s burgeoning Latin population. The schedules have been ghettoised so that South American telenovelas are simply bought up and served on specialist Spanish-language channels. But their popularity has alerted the network moneymen to a potential untapped seam.

Ugly Betty has been the first show to try to channel that crossover potential. The Mexican actress Salma Hayek, who is the show’s executive producer, began her career in telenovelas. “Although there are some things for the Latin market to see, I think the potential that’s out there has not been tapped into,” Hayek says. “We’ve been trying to bring the Latino experience to television for a long time now. And it’s been difficult, so we thought this would be the perfect bridge where we could bring something that all the Latin community would feel is something of theirs. It’s causing — I already know this for a fact — a lot of excitement in the Latin community; they can’t get enough of Betty. So people who have seen it before are still tuning in to this one because it’s different but it feels close to home.”

Hayek and her writers have rewarded them with a hilarious but tender portrayal of Betty’s family life that becomes a foil to the primped-perfect vacuousness of life at Mode. And viewers who might have seen previous incarnations of Betty are rewarded, in Ferrara, with a new Latino icon.

It’s Ferrara’s performance that keeps Ugly Betty on the credible side of cartoonish, and she has already been nominated for this year’s Golden Globes. A 23-year-old child of Honduran immigrants (the youngest of six), she says that much of Betty is grounded in her own experience.

“I had a very mixed childhood,” she says. “We lived in this Jewish community and I didn’t exactly feel like I fitted in. But then I would go to school, and I didn’t really fit in with the Latin girls either, so I didn’t know where I belonged. I think Betty experiences that a lot too.

“I get a lot of people who come up to me — young women, men, gay men — who feel out of place in certain circles, who know what it feels like to be on the outside and to doubt yourself constantly. Maybe that’s why this has been so successful — there’s something real about this character.”

WHO’S WHO IN BETTY’S WORLD

Betty Suarez
(played by America Ferrara)
The fish-out-of-water Latina magazine assistant eager to get ahead in journalism but derided by pretty much everyone around her. Lives with her father Ignacius, savvy sister Hilda and hilariously camp 12-year-old little brother Justin.

Christina
(Ashley Jensen)
Yes, Maggie from Extras goes transatlantic, popping up to play one of the good guys. Christina works in the repairs department at the magazine and is Betty's fairy godmother and confidante.

Daniel meade
(Eric Mabius)
The editor-in-chief of Mode. A dedicated playboy, under attack from all sides but ably assisted by the one woman who has never caught his eye — Betty.

Bradford meade
(Alan Dale)
Pater familias of the Meade publishing company, monitoring the progress of his faltering, wayward son with interest and no little concern. May also have unseated Mode's previous editor by dubious means.

Wilhelmina slater
(Vanessa Williams)
Devilish, impeccably clad creative director at Mode, on a mission to bring down Daniel Meade after she was passed over for his job.

Channel 4, Friday, 9.30pm (played by America Ferrara)