But, in a recent interview with The Zach Sang Show, Niall reveals his biggest secret of all: he isn't a natural blonde.
When hosts asked if he will bring back his blonde hair, he answered with, "I keep getting asked that, I fell like that's the general consensus that I should. Actually, I do miss the blonde. But I think I just got bored of every month having to go sit there for like three hours [to dye it]."
Who would've known?
He continued, "It's a pain in the a**, I may as well just leave it the way it is.
"I started doing it when I was like 12 or 13. So 10 years is a long time putting that crap in your hair."
True that Neil. True that.
Personally, we adore Niall as a brooding brunette.
What do you guys prefer? Blonde or brunette Niall? Let us know in the comments.