#13: Turned Pro at 20
After a stellar amateur career, including three U.S. Amateur Championship wins, Tiger Woods turned professional in August 1996 at age 20. He immediately signed lucrative endorsement deals with Nike and Titleist, making him one of the most marketable young athletes in sports.

His arrival on the PGA Tour was meteoric, and he wasted no time making an impact. That same year, he won two PGA Tour events and was named PGA Tour Rookie of the Year. His famous catchphrase, “Hello, world,” introduced him to the public, beginning an unparalleled golf career.
