The frock stars who rocked - and shocked - at the Oscars

The eyes of the fashion world will be on the red carpet at the Academy Awards on Sunday to see what gowns - and suits - will be turning people's heads.

How many of this year's attendees, though, will try to top the outfits of the past that made a lasting impression - and not always for the best reasons?

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One of the most outrageous gowns in Oscar history must surely be the infamous dress that Icelandic pop star Bjork swanned in on in 2001.

Marjan Pejoski's creation was roundly mocked at the time but later took pride of place at a Bjork retrospective at New York's Museum of Modern Art.

Two years before winning her Oscar for Moonstruck, Cher turned up to present one in a startling Bob Mackie creation topped with a massive feathered headdress.

"As you can see, I did receive my Academy booklet on how to dress like a serious actress," she joked before giving Cocoon's Don Ameche his supporting actor Oscar in 1986.

Australian costume designer Lizzy Gardiner deserved a lot of credit in 1995 for attending the Oscars in a dress made up of 254 expired American Express Gold cards.

Gardiner, who shared her award for The Adventures of Priscilla, Queen of the Desert with fellow Aussie Tim Chappel, later auctioned off the gown for charity.

Angelina Jolie went out on a limb by revealing a bare leg as she arrived at the 2012 Academy Awards in this black Atelier Versace ballgown.

Her exposed flesh swiftly went viral, with online pranksters adding it to images of everything from the Statue of Liberty to Whistler's Mother.

Celine Dion certainly reversed the trend at the 1999 ceremony by wearing a white Christian Dior tuxedo - backwards.

In an interview, the singer said she was only wearing her diamond-encrusted sunglasses because their makers had pledged $50,000 to one of her favoured charities.

Not to be outdone, South Park creators Trey Parker and Matt Stone dragged themselves down the red carpet at the 2000 Oscars as Jennifer Lopez and Gwyneth Paltrow respectively.

Parker's green gown mirrored the one Lopez had worn at that year's Grammys, while Stone's pink confection aped the dress Paltrow had won an Oscar in 12 months earlier.

Gwyneth Paltrow returned to the Oscars in 2002 in a gothic Alexander McQueen number she hoped would bring "a little bit of punk" to the occasion.

"I still love the dress but I should have worn a bra," the actress let slip 11 years later.

More recently, music star Pharrell Williams refused to be outflanked at the 2014 ceremony by turning up with wife Helen with a pair of Lanvin shorts.

By the time he came on stage to perform his Oscar-nominated song Happy, though, he was back in his more familiar casual gear - and hat.

And then there is Jenny Beavan, the British costume designer who Stephen Fry ungallantly likened to "a bag lady" at last year's Bafta Film Awards.

Undeterred, she rocked up at the Oscars two weeks later in a leather jacket adorned with a flaming skull. "I look ridiculous in frocks," she said later.