Justin Bieber is known for his hair among many other things. When he hit the scene as a teen phenom he was known for his shaggy look and even coined the term "hair flip" to describe the way he kept his locks out of his eyes. After years with his signature 'do, he switched things up with a shorter style, which has been popular with his female fans. Sadly, Beliebers may not be pleased with him after his latest trip to the hairdresser. (Photo by Mike Windle/Getty Images for Variety)
Whoa! The Biebs' new style certainly took us by surprise. Justin Bieber hit the town with a brand new bleached hairstyle in early December and certainly shocked many of his fans. Do you like the look? (Photo by Jerod Harris/Getty Images)
Sean Penn has always had nice locks, but we're used to his typical brown, center-parted style. (Photo by Frazer Harrison/Getty Images)
In December, Penn, 54, took a walk on the lighter side and stepped out with this honey-colored look. The warmer color seems fitting for his California cool personality. (Fameflynet)
Country star Jake Owen had worn his hair long and shaggy since his debut album in 2006.
(Photo by Chris McKay/Getty Images)
Jake's own nephew said that he was unrecognizable after a dramatic buzz cut removed his signature "George of the Jungle"-esque locks.
(Photo from Twitter/Jakeowen)
Sports Illustrated model Kate Upton is known for her gorgeous looks and long, blonde locks. Despite how lovely she looks, the 22-year-old decided to ditch her signature style this year in favor of a new crop. (Photo by Dave Kotinsky/Getty Images for the Daily Front Row)
That's quite a cut, Kate! The stunning model showed off a new shoulder-length chop on Instagram in late November. The sweet style seems to be a hot trend among many celebs. (Photo by Han Myung-Gu/WireImage)
Surprise Vanessa Hudgens is playing with her strands. The former "High School Musical" actress, 25, has enjoyed dozens of styles but she's maintained a pretty classic 'dark do for several years. After a quick switch to red earlier this month, Hudgens headed back to the dark side but made another change.
She got bangs! Hudgens looked hot to trot with a new fringe and face-framing bangs. V.Hudg debuted the look on Instagram in November. "
Jessica Alba, 33, is no stranger to hair experimentation, but the brunette babe has been enjoying the darker side for several years. Nonetheless, The Honest Company founder tried out a lighter look in November 2014. (Photo by Jason LaVeris/FilmMagic)
Alba rocked a honey-colored mane and the new look certainly gives her a more youthful appearance. Do you like her brightened tresses?
BEFORE: Jessica Simpson has always been a fan of long locks, but the singer-turned-fashion designer made a bold move this October. (Photo by Raymond Hall/GC Images)
AFTER: The blond bombshell lopped off her tresses for this modern 'do. She debuted the new look on Instagram and titled the photo, "Short hair don't care... Cut by my favorite @roqchop and blondie by the best of all time @ritahazan."
BEFORE: Lauren Conrad has always been a California girl and loved her long, blond, straight locks. (Photo by Valerie Macon/Getty Images)
AFTER: Conrad got hitched and that wasn't the only change she was ready for. The gorgeous gal showed off her shorter 'do and titled her Instagram snap, "Got my first haircut in years."
BEFORE: Conrad's "Laguna Beach" pal Kristin Cavallari also was a fan of her long hair until she went through a major life event.
AFTER: It looks like Kristin was ready for a change after welcoming her second kiddo. Mrs. Jay Cutler lopped off her locks and also titled her Instagram post, "Short hair don't care."
BEFORE: "High School Musical" star Ashley Tisdale is best known for her lovely tresses. In fact, she even named her production company after her famous mane: Blondie Girl Productions.
AFTER: The 29-year-old actress didn't chop her hair, but she did add a striking new color to it! Tisdale debuted a set of purple highlights in September.
BEFORE: The "California Girl" had been sporting dark raven tresses for several months before she made a wild switch.
AFTER: The hair chameleon is no stranger to experimentation and debuted a green color in April 2014. Perhaps she was rounding out her long list of "prismatic" colors!
BEFORE: She's just a blue-haired babe! Nicole Richie has been rocking blue locks for quite some time, but the 33-year-old actress decided to try out a new color of the rainbow in October. (Photo by Josiah Kamau/BuzzFoto/FilmMagic)
BEFORE: Lena Dunham has been keeping her hair a very normal shade of brown in order to film her hit HBO show "Girls." But once filming wrapped, she was clearly ready to try something new. (Photo by Steve Sands/GC Images)
AFTER: Well, that's quite a change. Dunham opted out of her boring brown color for a fun Kermit shade. Do you like the look? (Photo by Stuart C. Wilson/Getty Images)
BEFORE: Britney Spears has been rocking a long ponytail for as long as we can remember, but after years with a lengthy style she went for something a little more edgy. (Photo by Adam Jagielak/Getty Images Poland/Getty Images)
AFTER: The 32-year-old popstar showed off a sleek new bob at the launch of her lingerie collection in September. (Photo by Sascha Steinbach/Getty Images)
BEFORE: Elle Fanning has been sporting the same locks as her older sister Dakota for years, but when she finally hit her stride this year in her starring role in "Maleficent" things got wild. (Photo by Steve Granitz/WireImage)
AFTER: The 16-year-old cutie has been testing out a chestnut color as of late, which looks striking against her fair skin. (Photo by Jason LaVeris/FilmMagic)
BEFORE: Dakota Johnson has been proving that blondes have more fun for years with her layered do... (Photo by David M. Benett/Getty Images for Eco-Age/Green Carpet Collection)
BEFORE: Gabrielle Union has been sporting her side-swept look for years while "werking" the Hollywood scene.
AFTER: But the sirens of screens both big and small has since decided to go for sleek locks with a touch of color and a blunt bang.
BEFORE: Known for her blond, curly mane since she starred in "E.T. the Extra-Terrestrial," Drew Barrymore has chosen to go for a more grown-up look over the years and has kept her curls relatively tame with an ombre color. (Photo by Axelle/Bauer-Griffin/FilmMagic)
AFTER: In September, the former child star traded in her flaxen beachy waves for a more polished style -- now in auburn! (Photo by David M. Benett/Getty Images for Eco-Age/Green Carpet Collection)
AFTER: But the "Trophy Wife" star has since gone for an edgier style with a slicked-back mohawk. She revealed her wild mane in August. (Photo by JB Lacroix/WireImage)
BEFORE: Long and luscious is the best way to describe Selena Gomez's signature look.(Photo by Jon Kopaloff/FilmMagic)
AFTER: But in September, the brunette beauty switched it up and added a little bang to her mega-hair mix.
BEFORE: A shiny, sleek, and black hairdo gives Camilla Belle a sophisticated flair. (Photo by Jon Kopaloff/FilmMagic)
AFTER: Yet, her brand-new loosened and lightened look shows us the starlet's sunny side. The 28-year-old actress showed off her fresh style in September.
Stars from Lena Dunham to Nicole Richie are dying their locks and changing up their hairstyles in time to welcome the crisp weather. Whether it's Richie's swap for a deep blue or Dunham's platinum blonde, take a look at some of the most striking transformations above.