The former president of Viacom, Karmazin is now the CEO of Sirius, the satellite radio company that merged with its chief rival, XM Satellite Radio, in 2008.

The son of a New York City cabbie, Karmazin grew up in a public housing project in Queens, attended Pace at night, and took his first job in advertising, he says, because the office was air-conditioned. He moved to radio when he took a job at WCBS-AM, quitting after management tried to put a throttle on all the commissions he was earning, and moved to WNEW-AM where he eventually rose to become general manager. In 1981, Karmazin was tapped to join a small company called Infinity Broadcasting, which owned six radio stations at the time. He built the company into one of the industry's largest over the next decade and a half, acquiring dozens of stations across the country and applying what would become his trademark formula: programming that was heavy on sports and shock jocks plus an obsessive focus on cutting costs. Karmazin minted stars during his tenure at Infinity: In 1985, he picked up Howard Stern after he'd been fired at NBC and took him national, an unprecedented move considering radio hosts were almost exclusively local personalities at the time. He did much the same with Don Imus, who joined the Infinity family after it acquired WFAN. In 1996, after CBS/Westinghouse bought Infinity for $4.9 billion, Karmazin joined the combined company as CEO of CBS Radio, before angling his way up the ladder and assuming the title of CEO of CBS and, finally, as president and COO of Viacom. After butting heads with Viacom chair Sumner Redstone, he quit during the summer of 2004 and joined Sirius shortly thereafter.

A lifelong salesman who parlayed his sales prowess into a career as a media mogul, Karmazin had no intention of stepping out of the limelight when he left Viacom. After several failed attempts to take it easy, he was named CEO of Sirius Satellite Radio in November 2004, replacing Joseph Clayton. With satellite radio still struggling to gain momentum, he orchestrated a $5 billion deal to unite Sirius with its rival XM Satellite Radio, a transaction that was tied up in regulatory red tape for more than a year before finally getting clearance from the monopoly-wary Justice Department in March 2008. Karmazin assumed the CEO role at the combined company. Impatient, aggressive, obsessive, imperious, tight-fisted: they're the traits that have made Karmazin an extraordinarily difficult boss and an extraordinarily effective corporate manager over the years. The sort of boss who used to regularly review the phone and travel bills of his underlings, his obsessive focus on the bottom line earned him the respect of shareholders, although it never made him the most diplomatic corporate executive. "Mel Karmazin is as blunt as a punch in the nose," Dan Rather once said. [Image via Getty]