Australian-born producer, personal manager and music executive whose blockbuster hits with the Bee Gees and work on the films “Saturday Night Fever” and “Grease” made him one of the most successful impresarios of the 1970s. He was a producer of the 1975 film “Tommy,” based on the Who’s concept album of the same title, and in 1971 produced “Jesus Christ Superstar” on Broadway, establishing its longhaired creators, Andrew Lloyd Webber and Tim Rice, as emergent auteurs of the rock-opera era. In 1966 he became the manager of Cream, the rock supergroup that included Mr. Clapton, Jack Bruce and Ginger Baker, and was briefly associated with the Beatles. Brian Epstein, the Beatles’ manager, had merged his company with Mr. Stigwood’s, but after Mr. Epstein died in 1967 the group started its own company, Apple Corps, and Mr. Stigwood formed the Robert Stigwood Organization and its affiliated label, RSO. He also signed the Bee Gees, who had been child stars in Australia, shortly after their arrival in London in 1967, and promoted young pop stars like David Bowie and Rod Stewart.