Jamie Kellner, a media executive who helped build Fox Broadcasting into a thriving television network with shows such as Beverly Hills, 90210 and
The Simpsons — and who went on to create the WB network, known for the angsty Dawson’s Creek and Buffy the Vampire Slayer — died on June 21 at his home in Montecito, Calif., near Santa Barbara. He was 77.

The cause was cancer, said Brad Turell, a family spokesman.

Kellner was one of the most successful television executives of his generation, whose knack for capturing young viewers — first men at Fox, then women at WB — lured viewers away from the Big Three networks that had ruled television for nearly 40 years.

He believed ABC, NBC and CBS were ignoring viewers under 35 and were hamstrung by middle-of-the-road taste.

Rupert Murdoch, Fox Inc’s owner, and Barry Diller, its chairman, recruited Kellner from the television syndication business in 1986 and installed him as president of the Fox Broadcasting Company.

Its aspiration to be the first new TV network since ABC in 1948 was broadly derided. But from the debut in 1987 of its first series, the lowbrow family sitcom Married… With Children,” which was shown on six Murdoch-owned stations and a string of independent ones that Kellner helped stitch together, the new network began stealing the Big Three’s audience.

By 1992, with shows like Melrose Place, about the social lives of 20-somethings, Fox was #1 with viewers 18 to 34.

He resigned in 1993 after seven years at Fox and within months was conjuring up
WB, officially the Warner Brothers Network.