Co-founder, Netscape, Opsware, Ning, Andreessen Horowitz
Rank change: Up
NEXT: 2. Mark Zuckerberg
Long before there was a Zuckerberg, Andreessen helped create the building blocks of the web; his Mosaic led to the first commercial browser. Andreessen faded from the scene for a
time after Microsoft squashed Netscape, but he's back now: A-list venture capitalist and director at Facebook, Skype, and Hewlett-Packard, where he served as the public face of the
angry board in dismissing CEO Mark Hurd.
TV addiction: Mad Men. Andreessen had a bar installed in his new office and owns a record player that appeared on the show.