Rihanna is many things -- she's one of the most glamorous international pop stars in the world, she's Katy Perry's BFF, and since she kicked off her "Last Girl on Earth" tour this summer, she's also become a red-headed coif chameleon. Ever since RiRi debuted her short crimson crop in June, her hair has steadily "grown" longer and longer (kind of like Fashion Fever Barbie, whose hair grows 8 inches at the push of a button!). When she showed up on MTV this week sporting butt-length locks, we had to wonder: is the end of the road for Rihanna's redheaded adventure? Only time will tell. In the meantime, let's take a look back at the evolution of the pop princess's scarlet strands.