I really can't believe that I haven't mentioned Dana White before! Not only is he Sly, but he brought us the exciting sport that many of us watch; the Ultimate Fighting Championship.
According to
Wikipedia:
White has a background as an amateur boxer, but he later gave up as an active fighter and did not turn pro. In 1992, White established Dana White Enterprises in Las Vegas. He owned three gyms in the Las Vegas area, and using his experience in boxing he trained boxers and taught boxercise classes. He also promoted boxing events and managed boxers, eventually including mixed martial arts fighters as his clients.
As a manager for UFC fighters Tito Ortiz and Chuck Liddell, White learned that Semaphore Entertainment Group, the parent company of the UFC, was looking for a buyer for the UFC. White soon contacted Lorenzo Fertitta, a childhood friend, an executive at Station Casinos, and a former commissioner of the Nevada State Athletic Commission. Within a month Lorenzo Fertitta and his older brother Frank Fertitta III bought the UFC, with White installed as its president.[2] White currently owns 10% of Zuffa, LLC, the entity the Fertitta brothers created to own and manage the UFC.