You may have the feeling that Silicon Valley favors young, sweatshirt-wearing tech founders who drop out of college to start their own companies. And recent stories in the The New York Times Magazine and The New Republic give the distinct impression that ageism is rampant in the tech world.

Although venture capitalist Fred Wilson writes on his blog that he'll fund anyone at any age if he likes their idea, it has been suggested that some VCs have an unwritten rule about only offering startup capital to younger founders. Fortunately many prominent entrepreneurs in a variety of industries have managed to make it big over the years despite starting out at a relatively advanced age. Below, check out how old some founders were when they launched their now well-known companies.

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