Our second self-made billionaire woman on this list is Sara Blakely. Her path to fame was the invention of a now widely-used product, and an unexpected celebrity endorsement that sent her sales figures through the roof. She's banked $1.25bn via 'Spanx,' the underwear company she founded, which helps other women ensure their bodies stay contoured below whatever they're wearing. Blakely was 27 when she came up with the idea behind the garment. Putting them into production cost her every penny she'd ever saved; a comparatively meager $5000.
Anything that helps women to appear thinner and guard them against the effects of bloating on a night out was always bound to be popular with buyers, but she couldn't have wished for a happier accident when it came to building brand awareness. Television legend Oprah Winfrey, who hadn't been paid to do so, publicly stated they were a vital part of her wardrobe. After that, the orders started rolling in and never stopped.