CEO, News Corp.
Why he matters: Never bet on what Murdoch will do next. His 2005 purchase of MySpace for $580 million was widely mocked -- until traffic kept increasing and Google shelled out nearly three times as much to buy YouTube.
Now Murdoch is trying to buy Dow Jones, publisher of the Wall Street Journal, for $5 billion. A foolish play when everything seems to be migrating to the Web? As we said, betting on Murdoch's next move is risky business. But betting on his long-term success often pays off.