Geri Halliwell singing with the Spice Girls at the 1997 Brit Awards. Photo: Dave Benett/Getty Images

Talk about girl power! In a surprising new poll, the micro-mini Union Jack dress worn by Geri "Ginger Spice" Halliwell has been declared the most iconic dress of the last 50 years.

In fact, Halliwell's red, white, and blue flag frock -- which she first wore at the 1997 Brit Awards -- proved to have more zig-a-zig-ah than any ensembles worn by American fashion icons like Michelle Obama, Julia Roberts, and Gwyneth Paltrow.

Hmm.. the poll was conducted by U.K. online fashion retailer and considering that the list includes Elizabeth Hurley's safety-pinned Versace, Kylie Minogue's hot pants, and Björk's swan dress, StyleList thinks perhaps the respondents left out a few key contenders.

But according to OffersSupermarket founder Eve Atkins, "Everybody remembers the moment Geri Halliwell hit the stage in that Union Jack dress. [StyleList's note: America? Not so much.] It made everybody watching the Brit Awards feel patriotic, plus she looked amazing."

Bjork (left), Jennifer Lopez (center), and Elizabeth Hurley (right). Photos: Granitz/WireImage | Scott Gries/ImageDirect | Dave Benett/Getty Images

According to Spice lore, the Union Jack dress -- often accessorized with a pair of red platform boots -- was created by Halliwell's sister, Karen. "I got sent this black Gucci dress and I thought, 'What am I going to wear? That's a bit boring," the singer recently said in an interview with Piers Morgan.

Marilyn Monroe (left), Audrey Hepburn (center), and Princess Diana (right).
Photos: 20th Century Fox Licensing/Merchandising / Everett Collection | Everett Collection | Anwar Hussein, Getty Images

"And then I thought, 'Oh, my God.' I just got a light bulb and I thought, 'Brits -- let's celebrate being British! And so literally I got my sister to stitch it; she stitched it onto the black Gucci dress. It's a tea towel, that's what it is!"

Clearly, that tea towel was nothing to sneeze at (it fetched an impressive £41,320 -- $59,000 U.S. -- at auction last year).

Here's a complete list of OffersSupermarket's 10 Most Iconic Dresses of the past 50 years:

1. Geri Halliwell – Union Jack dress – 82%
2. Elizabeth Hurley – Versace safety pin dress – 79%
3. Marilyn Monroe – White dress from "The Seven Year Itch" – 74%
4. Audrey HepburnBlack dress and pearls in "Breakfast at Tiffany's" – 67%
5. Lady Gaga – White outfit and wig worn to the Brit Awards – 63%
6. Princess Diana – Wedding dress designed by The Emanuel's – 58%
7. Kylie Minogue – Gold hot pants – 56%
8. Jennifer Lopez - Sheer green Versace dress worn to the Grammys – 53%
9. Björk - Swan dress worn to the Oscars – 49%
10. Cindy Crawford: Red Versace dress worn to the Oscars – 44%

StyleList still thinks these poll takers missed a few famous frocks worthy of consideration.

Seriously, how can anyone forget the pretty pink Ralph Lauren dress Gwyneth Paltrow wore to the 1999 Oscars, where she picked up the Best Actress golden statue for her role in "Shakespeare in Love?"

Or Julia Roberts accepting her 2001 Best Actress Oscar for "Erin Brockovich" in a black-and-white vintage Valentino?

Then there's one of the most iconic dresses in recent history -- Michelle Obama's stunning white asymmetrical Inauguration dress designed by Jason Wu.

Gwyneth Paltrow (left), Michelle Obama (center) and Julia Roberts (right). Photos: Jeffrey Mayer/WireImage | SAUL LOEB/AFP, Getty Images, Jim Smeal, WireImage

But we want to know which dress you think is number one. Do you agree that Halliwell's Union Jack mini deserves to reign supreme? Should Monroe or Hepburn have earned the top spot? Is shocking, as in a swan or safety pins, more iconic? Or were Paltrow, Roberts, and Mrs. O unfairly overlooked? Vote in our poll for your favorite.

Speaking of icons, see which star is going to play Marilyn Monroe in an upcoming movie.