Sienna Miller Debuts an Asymmetrical Bob

Leave it to Sienna Miller to give the ever-trendy bob an extra edge! Over the weekend, the star was spotted out in London with a graphic asymmetrical cut, which walked the line between a chin-skimming bob and a collarbone-length lob.When it comes to trying out (or starting) the next big trend in hair, Miller has no qualms over changing up her own 'do. She's been a platinum blonde, deep brunette, and just about every shade in between--including pastel pink--and has even chopped her long layers into a pixie to play Edie Sedgwick in Factory Girl. "I'm really not too attached to my hair," she told InStyle previously. "If I worried about what people thought about my look, I'd get it all wrong."

See more celebrity hair makeovers in our gallery!

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Nicole Richie

WireImage; Courtesy Instagram/Nicole Richie

After posting an Instagram edited to look like she had purple hair in late February, Nicole Richie was inspired to make the change permanent in March. We can't decide what we like more: The bold color, or the fact that Richie's look mirrors the shade of her latest fragrance, NO Rules.

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Rosario Dawson

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Dawson cut her long strands into a chin-length bob in mid-December.

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Zosia Mamet

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True to her unconventional sense of style, Zosia Mamet took her platinum bob to a steely grey in December.

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Keira Knightley

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The actress kicked off December by taking her warm fawn strands to a deep chocolate hue.

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Kate Upton

Dimitrios Kambouris/Getty Images; Instagram/kateupton

The supermodel fooled us with this faux lob she debuted while on the promo tour for Game of War: Fire Age.

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Vanessa Hudgens

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The star gave her blonde ombre lob a fire-engine red tint.

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Eva Longoria

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Longoria walked the red carpet at the Global Gift Gala in November with a new shoulder-skimming cut.

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Sarah Hyland

Jason LaVeris/FilmMagic; Instagram/therealsarahhyland

She woke up like this! Using Queen Bey as her muse, Sarah Hyland went solid blonde in November.

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Jessica Alba

Jason LaVeris/FilmMagic; Instagram/JessicaAlba

Could another installment of Sin City be happening soon? After seeing Jessica Alba's Nancy-esque solid blonde hue in November, we certainly hope so!

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Hailee Steinfeld

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In November, Steinfeld chopped her mile-long strands into a shorter look that hit just below the shoulder.

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Frieda Pinto

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In November, Freida Pinto cut her signature layers into a collarbone-skimming lob.

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Faith Hill

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The Southern beauty debuted a bold pixie cut at the Country Music Awards in November.

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Beyonce

Pacific Coast News; Getty Images

From baby bangs, to a bob! Beyonce returned to her chin-length crop in November.

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Zac Efron

Douglas Gorenstein/NBC/NBCU Photo Bank via Getty; AKM-GSI

In November, Efron took his trademark crop to an undercut style, which featured shaved sides and long layers on top.

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Cara Delevingne

John Phillips/Getty; Jason Merritt/Getty

The model kicked off November by swapping her honey blonde highlights for a bold brunette hue.

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Ellen Page

Laura Cavanaugh/FilmMagic; Instagram/@lenadunham

What a change! The actress ended October by chopping her long layers into a dramatic pixie cut.

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Natasha Bedingfield

Getty Images (2)

Bedingfield chopped off her locks in October, saying it was time for a change.

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Shailene Woodley

Jason LaVeris/FilmMagic; Teach/FameFlyNet Pictures

Woodley returned to her natural brunette hue in late October.

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Jessica Simpson

Rommel Demano/Getty Images; Instagram/jessicasimpson

Simpson hopped on the lob trend in late October when she took her trademark Rapunzel layers to a sleek, colllarbone-length style.

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Lauren Conrad

Getty Images/Splash News

We collectively swooned when the style icon debuted a fresh, layered lob in October.

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Lena Dunham

BFAnyc;Pacific Coast News

The beauty and fashion risk taker swapped her short blonde 'do for this minty green shade for the Canadian leg of her book tour.

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Halle Berry

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In a departure from her trademark pixie, Halle Berry debuted a long bob in October.

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Sarah Michelle Gellar

Getty Images/Instagram

Buffy got a bob! In late October, Gellar took to Twitter to show off her tousled lob.

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Beyonce

Getty Images;Splash News

Suprise! Ever the risk-taker, Beyonce debuted a set of baby bangs while leaving Paris in mid-October.

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Zendaya

Tommaso Boddi/WireImage, Splash News

Zendaya made a major change in October, taking her long caramel-toned curls to a dark, graphic bob with blunt bangs.

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Jena Malone

Jemal Countess/WireImage, Andrew Toth/WireImage

The Catching Fire star kicked off October by debuting an equally-fiery auburn shade.

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Beyonce

F. Sadou/AdMedia/Sipa USA; Kevin Mazur/Getty Images for Global Citizen Festival

Beyonce kicked off October with a brand new set of bangs, and no surprise here, we thought they were flawless!

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Shailene Woodley

Getty Images (2)

The actress attended Paris Fashion Week in October with brand-new blonde highlights.

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Katy Perry

Getty Images/Instagram

Believe it or not, this is one shade we haven't seen Perry work before... The star kicked off fall by debuting a Muppet-inspired neon red hue.

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Britney Spears

Kevin Mazur/Getty Images for The Intimate Britney Spears; Patrick Hoffmann/WENN.com

Britney got a bob! The star cut her long layers into a sleek, chin-length style in late September.

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Sandra Bullock

Jason Merritt/Getty Images;FAMEFLYNET

Sandra Bullock ended summer by taking her brunette layers to a sunny blonde hue in late September.

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Elle Fanning

Jason LaVeris/FilmMagic

In late September, the younger Fanning sister swapped her trademark platinum hue for a warm brunette.

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Drew Barrymore

David M. Benett/Getty Images, Barcroft Media /Landov

In September, Drew Barrymore welcomed fall by unveiling her deep brunette hue.

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Zosia Mamet

John Lamparski/WireImage; Instagram

What better way to start New York Fashion Week than with a brand new 'do? In September, Zosia Mamet lightened her brunette strands to a bold platinum shade.

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Beyonce

Christopher Polk/Getty Images

Queen Bey ended the summer by cutting her long strands into a chin-length bob.

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Emma Stone

Monica Schipper/FilmMagic;Stefania D'Alessandro/WireImage

After letting her hair grow out over the summer, Stone ended August by revisiting her chin-length bob.

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Malin Akerman

JB Lacroix/WireImage; Frederick M. Brown/Getty

Hours before attending the HBO Emmys Party, Ackerman chopped off her long blonde locks in favor of a shorter, edgier 'do. "[It feels] amazing and freeing. I love it! I finally feel like I have a haircut that represents me," Ackerman told InStyle.com.

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Kerry Washington

Startraks Photo; Getty Images

Only moments before stepping out on the Emmys red carpet, Kerry Washington debuted brand-new ombre highlights. "When I saw Kerry, she just looked so young and fresh to me that I instantly thought of color and wanted to make her hair lighter," says her hairstylist Takisha Sturdivant-Drew.

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Rose McGowan

Vivien Killilea/WireImage, Jeffrey Mayer/WireImage

At the end of August, McGowan cut her chin-length bob into a pixie cut.

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Jamie Pressley

Tibrina Hobson/Getty Images, Cindy Ord/Getty Images

The actress chopped her short crop even shorter in late August.

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Kiernan Shipka

WireImage; Splash News

The young actress ditched her signature blonde locks (which she's had since making her Mad Men debut in 2007) for a darker brunette hue right before the 2014 Emmy Awards.

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Evangeline Lilly

Jesse Grant/Getty Images, Instagram/evangelinelillyofficial

To play Hope Van Dyne-a.k.a. Wasp-in the upcoming Ant-Man film, the actress debuted a graphic bob with blunt bangs in August.

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Lena Dunham

Jason LaVeris/FilmMagic;Lena Dunham Instagram

The Girls star went for a dramatic change, cutting her bobbed hair into this platinum bowl cut shortly after wrapping the series' fourth season.

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January Jones

January Jones added brow-skimming bangs to her trademark lob in August.

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Scarlett Johansson

Samir Hussein/WireImage; Splash News

In late July, Scarlett Johansson cut her long strands into a choppy pixie with sweeping fringe.

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Kesha

Splash News, Jason LaVeris/FilmMagic

No one can rock both of summer's hottest creative color trends quite like Kesha can! After a few months with lavender strands, the singer went for a pastel blue tone in late July.

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Lauren Conrad

Noel Vasquez/Getty Images; Instagram/laurenconrad

In time for her upcoming wedding, Lauren Conrad ditched her sombre (or subtle ombre) effect for a solid blonde hue.

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Rita Ora

Anita Bugge/WireImage; Dave Hogan/Getty Images

The ever-edgy singer added purple and blue dip-dyed extensions to her blonde bob in July.

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Chrissy Teigen

Kristin Callahan/ACE/INFphoto.com; Rob Kim/Getty Images

Chrissy Teigen jumped on the summer's hottest hair trend in July, chopping her long strands into a collarbone-skimming lob.

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Anna Paquin

Jason LaVeris/FilmMagic; Twitter/AnnaPaquin

From vampire to mermaid! Anna Paquin revealed her bold purple 'do in July. "@Auracolorist just fulfilled my teen dream of being a mermaid," she tweeted, along with a picture of her edgy new look.

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Olivia Palermo

Paul Zimmerman/WireImage; Jacopo Raule/GC Images

Our style muse was spotted at Couture Fashion Week in Paris, working pale golden highlights.

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Vanessa Hudgens

Instagram/vanessahudgens

When the High School Musical crew sung "We're All in This Together," they certainly meant it. Not long after fellow East High alum Ashley Tisdale chopped her hair into a lob, Vanessa Hudgens-a.k.a Gabriella Montez-followed suit in July.

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Kristen Stewart

Matt Baron/BEImages; Dominique Charriau/WireImage

Just before attending the Chanel Haute Couture show in July, Stewart chopped her long day-glo layers into a tousled pixie with sweeping bangs.

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Alyson Hannigan

Jason LaVeris/FilmMagic, Sasha Lazic/INFphoto

Willow is back! Hannigan brightened her natural auburn shade to a bold orange hue, reminiscent of her trademark look back in the Buffy days.

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Sienna Miller

Charles Sykes/Invision; PacificCoastNews

The actress put her own edgy take on summer's hottest haircut in July, debuting an asymmetrical version of the ever-trendy bob.

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Miranda Lambert

INFphoto.com; Rick Diamond/Getty Images

Lambert kicked off July by jumping on the bob bandwagon, taking her long layers into a chin-length style with sweeping bangs.

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Lily Collins

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Lily Collins got scissor-happy in late June, chopping her shoulder-skimming lob into a chin-length crop.

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Karlie Kloss

Courtesy of Instagram/Karlie Kloss

The model went solid blonde in late June.

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Jamie Chung

Parisa/Splash News; John Lamparski/WireImage)

In late June, Chung added ombre highlights to her long layers.

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Jennifer Love Hewitt

Jon Kopaloff/FilmMagic; Pablo/Goodwin/FAMEFLYNET PICTURE

The actress returned to her brunette roots in late June, then chopped her strands into a chin-length bob.

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Emma Roberts

Devlin Shand for Drew Altizer Photography/Sipa USA; Instagram/emmaroberts

In June, the actress took her platinum bob to a rich brunette tone.

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Nicole Richie

Paul Zimmerman/WireImage; Mariotto/INFphoto.com

After a brief stint with lavender strands, Richie went true blue in June-and even wore a coordinating outfit!

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Raven Symone

Wenn; Courtesy Instagram

What a vision! Symone took her dark strands to a pretty pastel hue in June.

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Ashley Tisdale

GC Images; FameFlynet Pictures

Tisdale jumped on the lob trend in June, chopping her lengthy strands into a shoulder-length cut.

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Hugh Jackman

Bruce Glikas/FilmMagic; Instagram/thehughjackman

New Hair 2014: See Celebrity Hair Makeovers!

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Nicole Richie

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Rosario Dawson

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Zosia Mamet

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Keira Knightley

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Kate Upton

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Vanessa Hudgens

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Eva Longoria

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Sarah Hyland

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Jessica Alba

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Hailee Steinfeld

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Frieda Pinto

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Faith Hill

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Beyonce

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Zac Efron

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Cara Delevingne

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Ellen Page

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Natasha Bedingfield

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Shailene Woodley

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Jessica Simpson

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Lauren Conrad

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Lena Dunham

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Halle Berry

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Sarah Michelle Gellar

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Beyonce

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Zendaya

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Jena Malone

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Beyonce

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Shailene Woodley

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Katy Perry

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Britney Spears

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Sandra Bullock

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Elle Fanning

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Drew Barrymore

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Zosia Mamet

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Beyonce

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Emma Stone

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Malin Akerman

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Kerry Washington

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Rose McGowan

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