It's easy to describe blue hair as equal parts dreamy and badass . It makes sense, as the hue can often veer moody, like you just stepped out of Hot Topic with a tub of Manic Panic. Meanwhile, pastel iterations can feel incredibly ethereal and lighthearted. Heck, even the " denim hair" trend of earlier this year could go either way. It's this bespoke characteristic that could be why tons of celebs have taken to the color in the past: Demi Lovato, Katy Perry, Kylie Jenner, and Gwen Stefani have all felt the blues.