LONDON — Robert Stigwood, the impresario who managed the Bee Gees and produced 1970s blockbusters “Grease” and “Saturday Night Fever,” has died. He was 81.

Stigwood’s office said he died Monday. The cause of death was not announced.

Born in Adelaide, Australia in 1934, Stigwood moved to Britain in the 1950s and soon became an astute player in Britain’s embryonic rock music industry.

In the 1960s he managed rock super group Cream and its guitarist Eric Clapton before signing brothers Barry, Maurice and Robin Gibb, collectively known as the Bee Gees, whose melodic folkrock achieved late-’60s success before a career slump.

Stigwood moved into theater – bringing Broadway hit “Hair” to the London stage – and film, producing cinema versions of Andrew Lloyd Webber-Tim Rice musical “Jesus Christ Superstar” and The Who’s rock opera “Tommy.”

He also produced the 1977 dancefloor drama “Saturday Night Fever,” with a soundtrack that brought the Bee Gees mega-stardom that reached a pitch as high as Barry Gibb’s signature falsetto.

That film and the Stigwood-produced “Grease,” released in 1978, also made John Travolta into one of the decade’s biggest stars.

Stigwood’s golden touch failed him with “Sgt. Pepper’s Lonely Hearts Club Band,” a Beatles-based movie musical which was a critical and boxoffice flop in 1978.

Sequels to “Saturday Night Fever” and “Grease” also underperformed, but Stigwood found success again in 1996 with movie musical “Evita,” starring Madonna as Argentine first lady Eva Peron.

Lloyd Webber paid tribute to Stigwood on Twitter, calling him a “great showman who taught me so much.”

Spencer Gibb – son of the late Maurice Gibb and Stigwood’s godson – described him as “a creative genius with a very quick and dry wit.”

“I would like to thank Robert for his kindness to me over the years as well as his mentorship to my family,” Gibb wrote on Facebook. “‘Stiggy,’ you will be missed.”

Funeral details were not immediately available.