The first Muslim woman to wear a hijab on the international high-fashion catwalk and the first woman to wear a hijab on the cover of of an American fashion or beauty magazine, Halima Aden has never played it safe in the modeling world. Aden grew up in a refugee camp in Kenya and now works as a UNICEF ambassador and activist. Though she's reportedly taking a break from the runway, she's walked for Gucci, Calvin Klein, Balenciaga, and many other top brands.