Jamie Kellner, who made his name as the only exec ever to create two broadcast networks — Fox and The WB (both of which also achieved profitability under his watch), died Friday at his home in Montecito, Calif. He was 77. Kellner had a tremendous impact on the television business in the 1980s, 1990s and early 2000s, and was considered an entrepreneur at heart as he built Fox and The WB, and then independently created the Acme Communications stations group, and for a time ran Turner Broadcasting as chairman and CEO (succeeding Ted Turner). Kellner’s impact includes landmark programming like “The Simpsons,” “Married… With Children,” “Cops,” “In Living Color” and “21 Jump Street” at Fox; the long run of pop cultural touchstones at the WB like “Dawson’s Creek,” “Buffy the Vampire Slayer,” “Gilmore Girls,” “7th Heaven” and “Felicity”; and he even worked with Lorne Michaels in the first syndication sale of “Saturday Night Live” while at Orion. He also was key to the early careers of creative...