It's a battle of the green-haired singers! Both Katy Perry and Adam Lambert are known for their outrageous styles and often-changing hair colors, and this time, the pop stars both dyed their hair green within a week of each other. The 'Dark Horse' singer colored her locks "slime green," while the 'American Idol' alum went for a bluer shade of teal. Who rocks the green hue best?

Katy Perry dyed her hair a color she dubbed "slime green," but to us, it actually looks a little more neutral and not as neon as we were expecting. But still, Perry -- who is known for her bold hair choices -- makes the look her own, showing off the almost army-green hue in short waves. The singer is also rocking kind of an ombre style: While her bangs and roots are her signature black color, her hair starts to ease into the green until almost her whole head of hair is that shade. We love how Katy Perry is always down to make bold fashion choices!

Adam Lambert's color is similar to Perry's but has a noticeably more teal bent -- not to mention, it looks completely different with his faux hawk and shaved sides. If anyone can pull off teal green hair, it's Adam Lambert, who honestly looks amazing with both the color and the punk-rock cut. While he's experimented with various different shades over the years, we think the green is one of his best yet. It should totally stick around for a while.

Which pop star pulls off green hair best? Cast your vote for Katy Perry or Adam Lambert in the poll below!

See Katy Perry's Green Hair

See Adam Lambert's Green Hair