"Black is certainly the gothic colour par excellence," writes fashion historian Valerie Steele in Gothic: Dark Glamour (Yale University Press, $47.95). The book was published to accompany an exhibit of the same name that just opened at the Museum at the Fashion Institute of Technology in New York, which Steele also curated.

Black, black, black - Gothic: Dark Glamour is chockablock with black. There are black dresses by Galliano, Givenchy, Gareth Pugh. There are black dresses by designer Ann Demeulemeester, the so-called "Dark Queen of Belgian Fashion." There are mourning dresses and jet jewellery from Victorian days. Even the endpapers are black.

But beware! "Not all black clothes are gothic," Steele says, "nor are all gothic fashions black." Gothic is more than a colour; according to Steele, it's an esthetic that embraces the many moods and meanings of black: death, defiance, devilry, and dandyism. Victorian mourning gowns of mauve are gothic; so, too, are memento mori such as skulls and skeletons.

In gothic fashion, black is more than black - it's blackness itself, the dark side embodied in a single sombre shade. And it's flattering - who doesn't look good in it? Steele believes that gothic fashion is able to embody the essence of death because fashion and death are cut from the same cloth. Fashion, she says, is a form of death, an artful, artificial form: It is constantly dying so that it can come back in a new silhouette, a new shape, a new style. All fashion is undead. All fashion is a Frankenstein monster.

"The uncanny is ‘nothing new,'" Steele says, quoting Sigmund Freud, "but on the contrary, ‘something which is familiar,' which has been ‘repressed,' and which recurs."

If the uncanny recurs, then the gothic is the uncanniest fashion of all. The first goth was Satan - the Dark One, the Prince of Darkness.

"Throughout world history," Steele writes, "black has been associated with night and darkness, and, by extension, with death, danger and evil." She notes that until the 19th century, black dye was dear. Only the wealthy were able to buy black cloth. Black was the colour of Beelzebub - and of nobility.

Byron wore black. Black perfectly captured the poet's reputation as a libertine and a rebel. Baudelaire wore black. It was said that he resembled "Byron dressed by Beau Brummell." Byron was a Romantic poet; Brummell an English dandy who revolutionized the cut of menswear in the early 19th century. Baudelaire was a bit of both: a red-blooded rebel who comported himself with an air of indifference, of sang-froid, of froideur.

Birds of a feather: Byron, Baudelaire, Beau Brummell - and Siouxsie Sioux? "The most important contemporary manifestation of the gothic is the goth subculture," asserts Steele, "which developed in the late 1970s." Siouxsie Sioux started out as a punk, an acolyte of the Sex Pistols. She wore bondage gear and PVC. After 1976, when she started singing with her own band, the Banshees, she developed a more macabre, mysterious look. She mixed and matched pieces of vintage Vivienne Westwood with vintage Victoriana. With her pale, powdered face, she resembled a character from The Cabinet of Dr. Caligari; with her black-rimmed eyes, she resembled Theda Bara, the lascivious vamp of silent movies.

Along with a few other figures from the post-punk scene - Peter Murphy of the band Bauhaus, Ollie Wisdom of the band Specimen, which opened the Batcave club in London - Siouxsie created the classic goth costume. It caught on with disaffected kids across the world, loners and losers who longed to be poets and rebels and dandies. It was codified as completely as Victorian mourning had been. In 1884, a widow in deep mourning could wear only black crepe; after a year and a half, purple became acceptable. In 1984, a goth's hair had to be dyed bottle blond or blue black. Fishnet stockings for girls; skirts for girls and guys. Black was non-negotiable. Goths seemed to be grieving, but for whom? For what?

Siouxsie's look lives on. It has lasted longer and made more of an impact than any look Madonna or David Bowie has dreamed up. It won't die. Fashion designers continue to resurrect it. In Gothic, Steele details the influence of the goth scene on designers such as Alexander McQueen, John Galliano and Rick Owens. Anna Sui showed her Goth Collection in 1997. Oliver Theyskens, the Belgian designer, has been dubbed the Prince of Darkness for his spooky, slinky dresses. Theyskens's Gloomy Trips collection of 1997 included Victorian-inflected dresses embroidered with human hair. In 2007, London designer Gareth Pugh presented a coat accessorized with dead white rats. Last week, at New York Fashion Week, Frank Tell showed a Siouxsie-inspired collection. "Frankly, I'd do all black if I could," he told style.com, "but that seems a touch OCD, and it's also a more interesting challenge to put across a gothic mood using colour." In malls across America, Hot Topic stores peddle the silhouettes that Siouxsie donned decades ago, selling T-shirts of the cute 'n' cuddly goth cartoon character Ruby Gloom to tweens. Goth fashion has gone from shocking to schlocky, from froideur to fromage.

While the classic goth look may be mouldering, Steele sees it rise up in new and novel ways. Cyber goths wear reflective fabrics. Vampire goths wear fangs. Gravers are goths who incorporate the electric colours of ravers into their ensembles. The steampunk style combines the lace and corsetry of the Victorian goth with the goggles and gas masks of the industrial goth. Steele sees strains of goth in punk fashion, death metal fashion, psychobilly and rockabilly fashion.

Why does goth fashion never die? It can't; it is death itself. To Steele, all fashion is an uncanny recurrence, a gothic phantasmagoria. Which raises the question: If all fashion is goth, then don't all clothes - cruisewear, sportswear, bridal wear - count as goth fashion? If so, why bother buying an Alexander McQueen gown to look goth? Wouldn't a bathrobe be more comfortable?

• Gothic: Dark Glamour continues at the Museum at the Fashion Institute of Technology in New York until Feb. 21.