Grant Tinker, right, with his then-wife Mary Tyler Moore in 1976. (Associated Press)

Grant Tinker, a television producer and network executive who ushered in a new era of sophisticated prime-time programming in the 1970s and 1980s, championing such well-received series as “The Mary Tyler Moore Show,” “Hill Street Blues,” “Cheers” and “The Cosby Show,” and who turned around NBC’s flagging fortunes in the early 1980s, died Nov. 28 at his home in Los Angeles. He was 90.

NBC announced his death. The cause was not disclosed.

Mr. Tinker, who began his career at NBC during the dawn of the television era, later became an advertising executive who helped develop “The Dick Van Dyke Show” in the early 1960s. Several years after he married the sitcom’s co-star, Mary Tyler Moore, the two founded a production company, MTM Enterprises, that launched some of television’s most honored and successful programs.

Their first effort, “The Mary Tyler Moore Show,” debuted on CBS in 1970 and featured the personal and professional misadventures of a single woman working in a TV newsroom. The groundbreaking series, which brought the concerns of working women to prime-time television, went on to win 29 Emmy Awards during its seven seasons.

Three of the show’s spinoffs, “Rhoda,” “Lou Grant” and “Phyllis,” became critical and commercial hits, along with other MTM sitcoms such as “The Bob Newhart Show,” about a Chicago psychologist, and “WKRP in Cincinnati,” about the staff of a Top-40 radio station.

Grant Tinker with former wife Mary Tyler Moore in 1997. (Chris Pizzello/Associated Press)

Other producers, most notably Norman Lear with “All in the Family,” were stretching television’s sense of social awareness in the early 1970s. But Mr. Tinker, as president of MTM, was widely credited with bringing high standards and an upscale sensibility to prime time.

“For two different decades, he defined smart, independent producing on television, first at CBS and later at NBC,” Ron Simon, curator of television and radio at the Paley Center for Media in New York, said in an interview. “He didn’t interfere with creativity. He gave total freedom to his writers and producers and helped define television as a writer’s medium.”

Mr. Tinker often said his only talent was finding talented people and letting them do their jobs. Among those he hired were writers James Brooks and Allan Burns, who were crucial to the success of “The Mary Tyler Moore Show,” and Steven Bochco, the creator of “Hill Street Blues” and “L.A. Law.”

“Grant gave us blanket approval of anything we wanted to do, not just autonomy, but support,” Brooks told Time magazine in 1981. “He’s a pragmatist with a passion for quality.”

After his success at MTM, Mr. Tinker was named chairman of NBC in 1981. NBC was in last place among the three major broadcast networks of the time and was in such bad shape that its parent company, RCA, was thinking of selling it or shuttering it altogether.

Mr. Tinker took a patient approach, renewing shows that didn’t immediately find an audience, such as Bochco’s gritty police drama “Hill Street Blues” and the hospital show “St. Elsewhere” — both produced by MTM. Despite dismal early ratings, he renewed “Cheers,” a comedy set in a Boston neighborhood bar, and “Family Ties,” about aging hippies raising children in the 1980s. All became long-running hits.

He revamped NBC’s news operation and added prime-time blockbusters to the lineup, such as “L.A. Law,” the stylish detective series “Miami Vice” and, especially, “The Cosby Show.” The Cosby sitcom was the breakout No. 1 hit and established the network’s “must-see TV” comedy block on Thursdays for decades to come.

Grant Tinker, right, and Mary Tyler Moore in 1973. (AP/ASSOCIATED PRESS)

By the end of 1985, Mr. Tinker had transformed NBC from an industry laughingstock to TV’s most-watched network. Johnny Carson and David Letterman ruled late-night television, and “Today” had become the No. 1 morning show.

All five Emmy nominees for best comedy series in 1987 were developed under Mr. Tinker’s watch at NBC: “Cheers,” “The Cosby Show,” “Family Ties,” “The Golden Girls” and “Night Court.” (The winner was “The Golden Girls,” about four older women sharing a home in Florida.)

Mr. Tinker also improved NBC’s bottom line from $48 million in profits in 1981 — a quarter of CBS’s profits — to more than $400 million in 1986.

That year, NBC’s parent company was taken over by General Electric, and Mr. Tinker left the network. In a 1994 autobiography, ‘‘Tinker in Television,” Mr. Tinker deflected credit for his own good fortune.

“I just had the good luck to be around people who did the kind of work that the audience appreciates,” he said at the time. “The success just rubbed off on me.”

Grant Almerin Tinker was born Jan. 11, 1926, in Stamford, Conn. His father ran a lumber business.

He served in the Army Air Forces during World War II and graduated from Dartmouth College in 1949. He then joined NBC in New York, working in the mailroom, before moving into advertising.

After helping develop “The Dick Van Dyke Show,” which aired on CBS, he returned to NBC as a vice president of television programming in 1961. He and Moore were married in 1963, six years before they formed MTM, along with a third partner, Arthur Price.

Mr. Tinker’s first marriage, to Ruth Byerly, ended in divorce. He and Moore divorced in 1981. Survivors include his third wife, Brooke Knapp; four children from his first marriage; and numerous grandchildren and great-grandchildren.

After leaving NBC, Mr. Tinker formed a production company with the Gannett newspaper publishing conglomerate, but the only noteworthy success was the show “Baywatch.”

His production company folded in 1990 but Mr. Tinker kept a wary eye on television, admiring some shows and holding others (reality shows, in particular) in contempt for lack of redeeming social value.

Even when he was leading NBC, Mr. Tinker fondly recalled the heady days when he, Moore and others were developing new shows at MTM.

“I’ll always rather be a programmer,” he said in 1984. “At MTM, we were doing just the things we chose to do, and having some success. It was the best of all worlds. I didn’t have to wear a tie, and I never wore real shoes.”