What's Her Best Hair?

Leaving her tousled, casual-cool locks behind, the actress goes ultra-glam at the Grey Gardens N.Y.C. premiere, tucking under her long hair into a ’20s-inspired bob – and adding a veil – just for the night.

For over a year the actress has kept her hair a dark brown hue, but she hit the streets of L.A. this week with a new honey-blonde color.

The singer declared on Twitter that she shaved off one side of her long hair this week, “B/C I WOKE UP AND FELT LIKE IT!!! YEEEAHHH!!! LOL :)”

The 90210 star changed up her long bob by adding a center part and taking up the length at a book party for her friend Tori Spelling in L.A.

The singer gets sexy in N.Y.C., changing up her long, straight style with a face-framing shag with blunt bangs.

The newly-single star makes over her look, leaving behind her strawberry blonde hair color for darker auburn locks.

Mimi swaps her carefully styled curls for natural beachy waves at a benefit in South Africa.

The actress leaves behind the sleek bob she’d favored for months, adding instant length to her locks.

She usually plays up the blonde bombshell look with soft waves, but for a birthday party in L.A., the singer went wild with bold corkscrew curls.

The actress swaps her signature blunt bob for longer soft waves at the Bravo A-List Awards in L.A.

The actress gets ready for summer, cutting off inches and lightening up with warm blonde highlights.

The Oscar nominee does a little red-carpet shape shifting, trying out elegant ’30s-inspired waves one evening and then going for a ’60s high-society bouffant another.

She’s no stranger to changing up her hairstyle, but for a trip to Vienna, the actress went for a natural look with a cascade of soft, lighter curls.

When it comes to updos, No Doubt’s frontwoman usually goes for a classic undone style, but to perform on the Today show, she twisted up the back and bangs into edgy top knots.

For months the star has made a raven pixie do her own, but at a magazine party this week, she shook things up by bleaching her hair platinum and spiking it high.

Forget those signature sleek tresses! To celebrate the Met Gala, the supermodel went avant-garde with a chignon plopped stylishly above her forehead.

She may be famous for Blair Waldorf’s rich brown tresses, but this week Gossip Girl’s Queen Bee went back to her blonde roots.

The Hills star lightens up for spring, trading her signature dark brown tresses for sun-kissed locks.

The fashion chameleon breaks up her monochromatic raven hair with platinum highlights.

Never one to get stuck in a style rut, Posh slicks back her short do for a charity fashion event, then goes for natural volume and softly-swept bangs to unveil her latest Armani underwear ads.

Saying bye-bye to her signature bob, the actress adds over a foot of length and sweeps back her hair into a high-fashion ponytail for the Met Gala.

She typically prefers a head full of waves and volume amped up to 10 – but for a lunch in Beverly Hills with her grandmother-in-law, the newlywed puts her hair on the straight-and-narrow, taming it into a sleek style.

After trimming her long hair into a bob for spring, Berry got set for summer by chopping off even more inches for a pixie cut reminiscent of the short style she wore early in her career.

Hollywood’s golden girl leaves her beauty trademark behind, stepping out in L.A. with a bold new brunette do.

Same night, different do! The star hits the CW upfront presentation in New York’s Madison Square Garden with long, straight layers, then tries tousled waves for the afterparty later that evening.

The talk show host gives fans something to buzz about, changing up her honey-blonde hair to a chocolate brown.

“I wanted to look like the Versace ad where the girls had these blunt-cut bangs,” the former Cheetah Girl tells PEOPLE.com of her decision to trade her soft layers for a fashion-forward fringe.