Sara Blakely, the 41-year-old founder of Spanx, is now the world's youngest female self-made billionaire! Blakely's business began when she cut the legs off of a pair of tights to smooth her figure under white pants. "I needed an undergarment that didn't exist," she told Forbes. Now everyone from Oprah to Jessica Alba is a fan of the shapewear. Are you? Tell us if you helped Blakely make her billion in the poll below!