From the New York Times
Mr. Cassini had the longest career of any designer in America, covering seven decades. He achieved perhaps his greatest fame as the official wardrobe designer for Jacqueline Kennedy when she was first lady; he also designed clothes for Joan Fontaine, Joan Crawford and other Hollywood stars and women of great wealth. But throughout his career he also saw to it that his name appeared on ready-to-wear fashions that were affordable to average women.
A related article appears in WWD (subscription required).