10 celebs with bold hair colors

From Katy Perry to Rihanna, take a look at which stars opted for rainbow-bright color changes.

Brown, red or blonde? Those options are too limiting for some risk-taking celebrities. From Katy Perry to Rihanna, take a look at which stars opted for rainbow-bright color changes:

Katy Perry
Katy Perry changes her hair color like a girl changes clothes... literally. The pop singer seems to always match her locks to her bright, fun ensembles. Perry recently debuted her "slime green" 'do on Instagram, adding the emerald hue to her rainbow repertoire.

Singer Ke$ha has rocked various pastel hues, sometimes even going so far as to wear a few at the same time.

Whether her tresses are bobbed, buzzed, or bunned, E! host Kelly Osbourne's purple hue has become her trademark look. This soft lilac color became quite popular among celebrities; Nicole Richie, Ellie Goulding and Vanessa Hudgens have all given the shade a try.

Alecia Moore Hart, better known as Pink, morphed her hair color from full-on fuschia to a pink ombre to platinum. She'll forever be known for her signature 'do. After all, it's in her name!

Avril Lavigne is known for her punk style and stick straight hair. The Canadian singer has tried out a few colors from hot pink to neon green, but her classic black streaks are her style staple.

Reality TV star Lauren Conrad is now a beauty and style expert, so it's no surprise that she's dabbled with dyed hair. Conrad has tried a variety of ombre styles and has dip-dyed her hair pink once a year since 2012. She revealed another set of pale pink tips on her Instagram in April 2014.

From bright pink to electric blue, Demi Lovato has worn it all. Lovato's confidence explodes with every new shade -- her most recent dye job also includes a partially shaved head.

From leopard spots to a bold skunk stripe, singer Nick Cannon shows he is not afraid to walk on the wild side.

It's official: Rihanna would look amazing even if she wore a mop on her head -- it's hardly fair. The singer has been everything from a fiery redhead to a bubbly blonde, and she even opted for a black and blonde swirl.

Singer Nicki Minaj is a costume queen. She never shies away from vibrant colors or patterns, and her mane is no exception!