WENN - Dan Jackman / Getty - Chelsea Lauren / . 1 / 8
WENN - Dan Jackman / Getty - Chelsea Lauren / . 1 / 8

Stark contrast!

Zosia Mamet is following the lead of her capricious costar Lena Dunham by adopting a new platinum blonde hairstyle just in time for fall. The formerly brunette "Girls" actress, unveiled her tousled blonde bob, during Mercedes-Benz Fashion Week Spring 2015 on Thursday, Sept. 4.

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Mamet, 26, who plays Shoshanna Shapiro on the hit HBO series, wore a bright yellow dress with a jewel-encrusted bibbed neckline, which competed for attention against her new hue, to the HONOR fashion show in New York City.

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In August, Dunham went platinum with an equally drastic bowl cut hairstyle. She introduced the dye job on Instagram, which many of her followers originally assumed was a wig. Days later, Dunham confirmed the extreme hair change on the 2014 Emmys red carpet. Her shocking look came complete with a frothy bubble gum pink gown designed by Giambattista Valli.

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This is the second bold hair move Mamet has debuted in less than a year. For the 2014 Golden Globes in January, she pulled a surprise by hacking off her long shoulder-length strands for a wavy, loosely-styled cut.

Before that in 2013, the star broke her dye job virginity, temporarily going strawberry blonde for a role in Paul Downs Colaizzo’s Off-Broadway play, "Really Really." Mamet told the Associated Press, she never dyed her hair before: "The idea of dyeing it for the first time, when I'm doing a play for the first time felt great!"