Bob Stewart, a television producer who understood that Americans love to find bargains, learn secrets and win prizes, and who accordingly gave the country a raft of phenom game shows including “The Price Is Right” and the “Pyramid” franchise, died May 4 at a hospital in Los Angeles.

He was 91 and had respiratory failure, said his son Sande Stewart.

A former writer for radio variety shows, Mr. Stewart joined the Mark Goodson-Bill Todman Productions in the mid-1950s. In the next four decades, he masterminded some of the most popular game shows in TV history.

To critics, game shows are crass manifestations of American consumerism and even greed. To fans, who number in the millions, the shows are raw pleasure — a sort of sedentary sport in which Anyman (or woman) is always the star player.

“Bob had the pulse on America,” Fred Wostbrock, co-author of “The Encyclopedia of TV Game Shows,” said Saturday in an interview. “He had that skill to come up with a game that . . . anybody can play — word association, how much is the price of an object or who’s telling the truth. They’re actually simple games, if you analyze it.”

Bob Stewart, shown in the foreground of this 1956 photograph on the set of "The Price Is Right." (Courtesy of Fred Westbrock)

In 2010, Mr. Stewart was inducted into the Academy of Television Arts & Sciences’s Hall of Fame. The award recognized his work on Goodson-Todman programs including “To Tell the Truth” and “Password” and — later in his career, as the head of his own production company — “The $10,000 Pyramid.” The “Pyramid” programs alone racked up nine Emmy Awards, according to the Hollywood Reporter.

Mr. Stewart’s success stemmed largely from his powers of observation. In New York, where he worked in his youth as an all-purpose television writer, producer and director, he noticed a certain pattern shared by window shoppers. They would peer into donut shops and delicatessens, point to the item that struck their fancy, then turn to their companions and say: “What do you think it goes for?”

That ritual became the basis for “The Price Is Right.” Mr. Stewart pitched the idea to Goodson-Todman — a titan among game-show production companies — and the show debuted in 1956. It became perhaps Mr. Stewart’s most enduring success, with both daytime and prime-time episodes running for much of the next decade. A revival version hosted by Bob Barker aired from 1972 until Barker’s retirement in 2007, making it the longest-running game show in American history.

“The Price Is Right” exemplified the early years of American game shows. It was an era before flashiness took over television, and when studio audiences were riled into a lather by housewives’ ability to divine the price of Ajax foaming cleanser. More important, in Mr. Stewart’s estimation, were the TV viewers at home.

“Once you cause somebody at home to talk to the set aloud, even by himself or herself, then you’ve got a good game show,” he said in an interview for the Archive of American Television. “Make that person at home yell something. . . . You want them to say ‘It’s number 2! It’s number 2! It’s number 2!’ before the moment of truth comes out.”

“The Price Is Right” was also a 1950s “sponsor’s dream,” a point noted in the “Encyclopedia of Television.” With rationing left behind after World War II, manufacturers were willing to provide goods in exchanges for plugs on the show. Contestants were handsomely rewarded, too, with prizes including houses, cars, cold cuts for a year and wheelbarrows full of silver dollars, Wostbrock noted.

Mr. Stewart’s son recalled one contestant who could not claim her prize. She was an African American woman, and she could not live in the house she won in a segregated Florida neighborhood.

If “The Price Is Right” let viewers root for regular people, “To Tell the Truth” invited them to revel in celebrity. In that show, which also debuted in 1956, a panel of celebrities was assembled and invited to examine three contestants, one of whom had a unusual job or personal background and two of whom were imposters.

Mr. Stewart told Wostbrock that he got the idea for the show by observing the guesswork about other people’s private lives that he noted in crowded elevators. The show ran until 1967 , another of Mr. Stewart’s signature accomplishments.

He also created “Password,” a show that debuted early in the 1960s and was hosted by Allen Ludden, husband of Betty White. According to the “Encyclopedia of Television,” it was the first show in which ordinary people teamed up with celebrities to try to win.

Mr. Stewart left Goodson-Todman in 1964 and started his own company, Bob Stewart Productions. The company created a total of 15 TV shows, the first of them being “Eye Guess.” He was best known for a show that began in 1973 called “The $10,000 Pyramid,” hosted initially by Dick Clark.

Popularity and syndication helped the show up the ante, allowing it to be renamed “The $20,000 Pyramid,” “The $25,000 Pyramid” and, by 1981, “The $50,000 Pyramid.” A breathless, Taboo-like show that (like “Password”) paired celebrities with common contestants, it was raucously popular. Washington Post television critic Tom Shales once wrote that the show “stands out in the annals of Game Show Americana and in a league apart from the flashing lights, the brzzzt brzzzt of the sleazy buzzers, the ga-ga, wow, and flutter of your typical refrigerator-winning arrested-adolescent contestant. To climb to the top of the Pyramid you pretty well had to know something.”

Over time, and as the original game-show audiences aged, interest in the genre waned. In the late 1970s and into the ’80s, networks began scaling back programming. Today, “The Price Is Right” is one of the last traditional game shows left standing. Mr. Stewart retired in 1992.

Isidore L. Steinberg — the L. did not stand for anything — was born Aug. 27, 1920, in Brooklyn to Jewish immigrants from Russia. He began going by Bob Stewart in the 1950s after being rejected for a television job because of what he believed was the employer’s anti-Semitism. He always regretted the decision to change his name, his son said.

One of his chief pleasures growing up in the Great Depression — and one of his family’s most prized possessions — was a radio. (Only his father was allowed to touch it.) Mr. Stewart saw a television for the first time at the 1939 World’s Fair in New York.

After service in the Army Air Forces during World War II, he attended radio-writing night school in New York on the G.I. Bill. Weeks later, in December 1946, the instructor helped Mr. Stewart get a job at a local radio station, and by the following year Mr. Stewart was teaching the same course. By the 1940s, he was so enamored with his work that he turned down a job in television because he couldn’t imagine leaving radio.

But by the late 1940s, television seemed increasingly appealing, and Mr. Stewart took a series of jobs with local programs in New York, including a variety show with Morey Amsterdam, who later became an actor with “The Dick Van Dyke Show.”

Mr. Stewart also wrote for the TV show “Songs for Sale” — a sort of precursor to “American Idol” in which a young Rosemary Clooney and Tony Bennett sang submissions from aspiring songwriters taking their shots at celebrity.

His wife of 46 years, Sara Abramowitz Stewart, died in 1990. His longtime companion, Anne-Marie Schmitt, died in 2006.

Survivors include three sons, Barry Stewart of Fort Lauderdale, Fla., Sande Stewart of Woodland Hills, Calif., and David Stewart of New Hyde Park, N.Y.; two grandchildren; and two great-grandchildren.

Mr. Stewart once recalled that when interviewing prospective contestants for his game shows, he often asked how they wanted their epitaphs to read. The only thing he could think of for his own, he said, was “The party’s over.”