Sumner M. Redstone, the billionaire entrepreneur who saw business as combat and his advancing years as no obstacle in building a media empire that encompassed CBS and Viacom, died August 11 at his home in Los Angeles. He was 97. His death was announced in a statement by National Amusements, the private theater chain company founded by his father.

Mr. Redstone had vowed never to give up the reins of his conglomerate, but in February 2016, he stepped away from managing it, and his daughter, Shari E. Redstone, took control of day-to-day affairs.

Beginning with a modest chain of drive-in movie theaters, Mr. Redstone negotiated, sued and otherwise fought to amass holdings that over time included CBS, the Paramount film and television studios, the publisher Simon & Schuster, the video retail giant Blockbuster, and a host of cable channels, including MTV, comedy Central, and Nickelodeon. At their peak, the businesses were worth more than $80 billion.