Kevin Plank

Under Armour founder Kevin Plank built a popular sportswear brand as the underdog competitor to Nike.Noticing his football teammates' sweat-soaked shirts, Plank came up with a lightweight, sweat-wicking shirt using fabrics from women's undergarments.In the mid 1990s he sold his first shirts from his grandmother's basement, exaggerating to early customers to make the company sound bigger. Plank, who is Under Armour's CEO, took the company public 2005; he owns a nearly 16% stake.He is building a 4 million-square-foot headquarters for Under Armour in Baltimore as part of a larger development called Port Covington.