Billionaire Marvin Davis, 79, a former oilman who sold his 20th Century Fox studios to Rupert Murdoch in the 1980s, died Sept. 25 at his Beverly Hills, Calif., home, after a long illness, his publicist said. The exact cause was not released.

Earlier this year, Mr. Davis's fortune was valued at $4.9 billion by Forbes magazine, in which he placed 85th on the annual ranking of billionaires.

He bought 20th Century Fox studios in 1981. In 1984, he recruited Barry Diller, then head of Paramount, to run the studio. The following year, he sold Fox to Murdoch, and it is now part of the media mogul's News Corp.

After the sale, Mr. Davis built and twice sold the 20th Century Fox Plaza in Century City, Calif., and over the years made attempts to buy CBS, NBC and Metro-Goldwyn-Mayer.

In 2002, he made a last attempt to reenter the entertainment business with an unsolicited and unsuccessful offer to buy the entertainment assets of Vivendi Universal, including Universal Studios, for $15 billion.

Born in 1925 in Newark, Mr. Davis graduated from New York University in 1947. After graduation, he joined his father in creating Davis Oil Co., a wildcat drilling operation that earned them billions of dollars. In the 1980s, the Davis family moved from Denver to Beverly Hills, where he started a second career in real estate.

An avid golfer, Mr. Davis owned the Pebble Beach Co., a seaside California resort that included four of the country's best-known golf courses. He sold the company for $841 million in 1990 to Japanese investors.

Mr. Davis and his wife, Barbara, established the Children's Diabetes Foundation in 1977 after their daughter Dana was diagnosed with the disease. Davis was also an active fundraiser for Democratic candidates.

Survivors include his wife and five children.

Actress Joan Collins was a guest at a charity gala to fight diabetes that Marvin Davis hosted in 2000.