The cause was cancer, said Lorraine Caggiano, his executive assistant. Mr. Casablancas, who lived in Miami, was being treated in Brazil.

Head-turningly handsome, Mr. Casablancas courted scandal in his own life as well, accused of having sexual relations with teenage models and pursuing a playboy's life of excess.

For 30 years, through the Elite Model Management agency he founded in Paris in 1972, he shaped the careers of models who became household names, among them Cindy Crawford, Naomi Campbell, Carol Alt, Linda Evangelista, Claudia Schiffer, Andie MacDowell, Kim Alexis, Paulina Porizkova, Iman, Heidi Klum and Gisele Bündchen.

By the end of its first decade, Elite had become a serious and brash competitor to the well-established New York agencies, like Ford and Wilhelmina, triggering a series of raids, defections and gossipy lawsuits that forever changed the modeling industry and were voraciously covered in the tabloids as the "Model Wars."

Mr. Casablancas was at the center of it all, unabashedly mixing business with his pleasure. Where Jerry and Eileen Ford, who founded Ford Models in 1946, had brought an almost puritanical sense of ethics to the modeling business, introducing modern accounting practices and standardized pay and working hours, Mr. Casablancas planted the flag of a provocateur, encouraging his young charges to enjoy a lifestyle of Champagne and wild parties, and sometimes more. He also made the most successful ones very rich.

"I had the understanding of a guy who loved beautiful women, and above all who liked the sensuality of it all," Mr. Casablancas said in a 2010 video interview with the blog Modelinia. "All of the other agents were either women or gay guys. They had their own approach, which in certain instances was probably superior to mine, but I had something I thought was unique. I looked at my models as women."

He was largely responsible for glamorizing the business and turning models into idols, their egos expanding in direct proportion to their earnings potential. In 1990, at the height of the supermodel moment, Ms. Evangelista, then married to Gérald Marie, the president of Elite in Paris, made a comment to Vogue that came to define the vainglorious world of modeling that Mr. Casablancas had created: "We don't wake up for less than $10,000 a day."

Mr. Casablancas demanded top dollar for his models, developing them as celebrities and media personalities, the stars of music videos and presenters on MTV. In 1988, to make Ms. Crawford a recognizable face beyond fashion, he encouraged her to pose for Playboy magazine. The ensuing publicity led to a job as host of "House of Style," and then a Pepsi commercial. In 1995, she topped the Forbes list of highest paid models, earning $6.5 million.

The success of Elite, with more than $100 million in annual model bookings during the years it was run by Mr. Casablancas, represented a turning point in modeling, for better and worse. As Wilhelmina Cooper, one of his rivals, said of the typical top model in 1978: "She is now picking or choosing who she wants to work for, instead of just taking what her agency tells her to."

Mr. Ford, who accused Elite of poaching models and sued the company in the late 1970s, described Mr. Casablancas's methods at the time as "sleazy."

Beyond his feuds with other agencies, Mr. Casablancas was frequently criticized for having sexual relationships with young models. His public affair with Stephanie Seymour in 1983, when he was 41 and she was 16, ended his second marriage, to Jeanette Christjansen, a former model and the 1965 Miss Denmark.

Mr. Casablancas scoffed at the criticism, but his reputation was severely tarnished in 1999 as a result of a BBC One undercover exposé that showed Elite's agents in Europe, including Mr. Marie, boasting of drug use and sexual conquests with young models. Though he was not implicated in the scandal, Mr. Casablancas resigned from the agency the following year.

This article has been revised to reflect the following correction:

Correction: July 20, 2013

An earlier version of a photo caption accompanying this article misspelled the surname of one of the models pictured with John Casablancas. She is Joan Severance, not Severence.