Long-time Microsoft developer who became the billionaire owner of independent video game company Valve Corporation. He's helped the company release such popular games as the Portal series and the Team Fortress series.
He developed Steam while working on Half-Life 2. He was called A Name You Should Know by Forbes in December 2010.
He earned a small fortune while working with Bill Gates at Microsoft, where he played an instrumental role in the development of the first three Windows operating systems.
He chose to drop out of Harvard University.
He fathered two sons with wife Lisa Newell.