The founder and CEO at 25, of the short-form blogging platform Tumblr, Karp is an American web developer and entrepreneur.
He dropped out of high school at age 15 and one year later he was the CTO of a company called UrbanBaby. Not only is he worth an estimated $200 million, the CEO proves he's more than just the brains after modeling for a J.Crew suit ad this season.
Wikipedia entry - David Karp
image: © Enrique Dans