Don Buchwald, a talent agent who further elevated the radio personality Howard Stern into the stratosphere of fame and wealth by negotiating a half-billion-dollar deal that sent him from terrestrial to satellite radio nearly two decades ago, died on July 22 at his home in North Egremont, Mass. He was 88.

His death was confirmed by his daughter Julia Buchwald.

“Everyone should have a Don Buchwald in their life,” Mr. Stern told The New York Times in a profile of Mr. Buchwald in 2018. “I’d never want to be without him, and I don’t need anyone but him. It sounds like a love song, but it is.”

Mr. Stern was Mr. Buchwald’s most famous client in a career in which he had represented actors like Ed Asner, Tony Curtis and Kim Novak.

In 1984, Mr. Stern was a shock jock in a rocky relationship with his bosses at WNBC-AM in New York and in need of more career help than his lawyers could provide. He called three agents. Only Mr. Buchwald was interested, and they agreed to meet.

“He turned to me and said, ‘You know, your career could be as big as Johnny Carson’s,’” Mr. Stern recalled. “I thought this guy might be a little bit nuts.”

Through a spokeswoman for his show, Mr. Stern said, “Don means so much more to me than I can possibly express in a brief statement. I will save all my words for my show.”