Britney's most memorable style moments

"Which song are you the most excited for?" tweeted "Glee's" next guest star, Britney Spears, to her legions of followers (almost 6 million and counting). And while we can't wait for the montage of her greatest hits on the Sept. 28 episode, it's the costumes that have us most excited! In honor her highly anticipated cameo, we've rounded up the most memorable of Britney Spears's style moments, both onstage and off. Sure we included the sexy schoolgirl look that Brittany (Heather Morris) will don, but with so many looks to choose from, how ever did the writers decide? Click through our gallery to relive the extraordinary style of Ms. Spears.

"Baby One More Time" video

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On the cover of the April issue of Rolling Stone magazine.

Performing at the MTV Video Music Awards

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"Sometimes."

Performing at the MTV Video Music Awards. Her costume was designed by David Dalrymple.

•InStyle.com: Britney Spears' transformation

•InStyle.com: Cute photos -- star moms & kids

•InStyle.com: 10 ways to look better naked

Britney wore a dress by Randolph Duke and an Oscar de la Renta shrug at the Grammy Awards.

Her MTV Video Music Awards dress was by Dolce & Gabbana.

•InStyle.com: Britney Spears' transformation

•InStyle.com: Cute photos -- star moms & kids

•InStyle.com: 10 ways to look better naked

Walking the red carpet with Justin Timberlake at the American Music Awards.

The infamous snake dance at the MTV Video Music Awards.

•InStyle.com: Britney Spears' transformation

•InStyle.com: Cute photos -- star moms & kids

•InStyle.com: 10 ways to look better naked

Performing at the halftime show of the Super Bowl.

On the red carpet at the MTV Video Music Awards.

•InStyle.com: Britney Spears' transformation

•InStyle.com: Cute photos -- star moms & kids

•InStyle.com: 10 ways to look better naked

Performing at the MTV Video Music Awards.

Britney wore a Roberto Cavalli dress to the NRJ Music Awards.

Pepsi commercial.

•InStyle.com: Britney Spears' transformation

•InStyle.com: Cute photos -- star moms & kids

•InStyle.com: 10 ways to look better naked

From the "Oops I Did It Again" video.

A scene from the "Womanizer" video.

•InStyle.com: Britney Spears' transformation

•InStyle.com: Cute photos -- star moms & kids

•InStyle.com: 10 ways to look better naked

Performing during the Circus Tour.