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Star-struck brands

Celebrity endorsements are a dime a dozen. Throw enough money at most movie or sports personalities and they're willing to put their name behind a product. But more and more stars of film, music and sports are more interested in starting their own businesses.

While the number of failed ventures by entertainers is considerable, several celebs have managed to defy the odds and become not just successful entrepreneurs—but titans of their industries, with companies that have multimillion- or multibillion-dollar valuations.

Certainly, their fame helps. But without a sound business plan and a quality product, no company can succeed. Here are some of the celebrities that have managed to carve out second careers for themselves in the start-up world.

By Chris Morris, special to CNBC.com
Posted 18 April 2015

Noam Galai | WireImage | Getty Images