Alex Trebek, who became known to generations of television viewers as the quintessential quizmaster, bringing an air of bookish politesse to the garish coli­seum of game shows as the longtime host of “Jeopardy!,” died Nov. 8 at his home in Los Angeles. He was 80.

The cause was pancreatic cancer, said Alison Shapiro Cooke, director of communications for “Jeopardy!”.

Mr. Trebek had suffered a series of health reversals in recent years, including two heart attacks and brain surgery, as well as his cancer diagnosis in 2019. He continued to host new episodes of his show until production was suspended in March because of the coronavirus pandemic, and then filmed socially distanced episodes that began airing Sept. 14.

For more than three decades, Mr. Trebek was a daily presence in millions of households, earning near-rabid loyalty for the intellectual challenge of his show, in which questions were presented as answers and answers were delivered in the form of questions. By the time of his death, “Jeopardy!” was one of the most popular and longest-lasting programs of its kind in TV history.

Mr. Trebek, the self-made son of a hotel chef, had no sequined co-presenter to match Vanna White on host Pat Sajak’s “Wheel of Fortune.” His show neither attracted nor allowed histrionics, no galloping, shrieking contestants such as those summoned to “Come on down!” on “The Price Is Right” with Bob Barker. Even the “Jeopardy!” theme song, one of the most recognizable jingles on television, was restrained in its dainty dings.

There was no “hot seat” like the chair for contestants on “Who Wants to Be a Millionaire?” with Regis Philbin — a show that “Jeopardy!” purists disdained for its elementary subject matter and inflated prize money.

On “Jeopardy!” there were only questions and answers — or rather, answers and then questions — leavened by the briefest of banter before Mr. Trebek directed his three contestants back to business.

He became known, a reporter for the New Republic magazine once observed, for his “crisp enunciation, acrobatic inflections [and] hammy dignity” as he primly — and with precise pronunciation — relayed clues in categories such as “European Cuisine,” “U.S. Geography,” “Ballet and Opera,” “Potent Potables” and “Potpourri.”

“The folding type of this cooling device became accepted in China during the Ming dynasty,” Mr. Trebek might declaim, as competitors raced to buzz in with the reply, “What is a fan?”

“Jeopardy!” was the creation of singer and talk-show host Merv Griffin, whose TV empire also included “Wheel of Fortune” and “Dance Fever.” His wife, Julann Griffin, proposed the show’s conceit. If players provided questions instead of answers, she said, then “Jeopardy!” would be safe from the high-profile cheating scandals that plagued TV quiz shows in the 1950s.

The Griffin brainchild aired on NBC from 1964 to 1975, then returned as “The All New Jeopardy!” from 1978 to 1979, both times with the stately actor Art Fleming as host. Mr. Trebek took over when the show was revived in syndication in 1984, also serving during his first several seasons as producer.

Much like his program, Mr. Trebek indulged in few frills. He favored conservative suits. When he shaved his signature mustache in 2001 — “on a whim,” he said — his viewership erupted in titillation.

The most exuberant flourish about the show might have been the exclamation mark in the title. Mr. Trebek, for his part, emitted few if any exclamations as he led contestants through the first round of clues; then a second, higher-stakes round dubbed “Double Jeopardy!”; and then “Final Jeopardy!,” in which players could wager all or some of their earnings on a single stumper.

“My job,” he told the Associated Press in 2012, “is to provide the atmosphere and assistance to the contestants to get them to perform at their very best. And if I’m successful doing that, I will be perceived as a nice guy and the audience will think of me as being a bit of a star. But not if I try to steal the limelight! The stars of ‘Jeopardy!’ are the material and the contestants.”

(Perhaps the show’s greatest stars were Ken Jennings, who reigned over the grid for 74 shows in 2004, claiming $2.5 million in winnings, and Watson, the IBM computer that defeated Jennings and another champion, Brad Rutter, in 2011.)

Fans who attended tapings of the show received a rare insight into Mr. Trebek’s dry humor when he held forth with them during commercial breaks, cutting up about how he didn’t “like spending time with stupid people,” which resulted in his having “very few friends.” He often regaled the crowd with tales of his DIY home-improvement projects.

He said his breakfast consisted of a Snickers and Diet Pepsi, or a Milky Way and Diet Coke. And he was not always as staid as he might have seemed, once tearing his Achilles’ tendon when he chased a burglar from his hotel room in 2011.

But to most “Jeopardy!” viewers, Mr. Trebek was akin to a neighbor they saw every day without becoming intimately acquainted. In a tribute to Mr. Trebek after his cancer diagnosis was announced, Jennings affectionately described him as “a riddle wrapped in an enigma wrapped in a Perry Ellis suit.” One of the few clues to his past was his slight Canadian accent.

George Alexander Trebek was born in Sudbury, Ontario, on July 22, 1940. His father was a Ukrainian immigrant, and his mother was French Canadian. In a memoir published in July, “The Answer Is . . . Reflections on My Life,” Mr. Trebek described a childhood marked by poverty and illness, including a painful form of rheumatism that he developed after falling into a frozen lake at age 7.

Mr. Trebek said that he considered becoming a priest but did not enjoy his experimentation with a vow of silence. “I was a very good student, but leaned more toward show business than anything else because I had a way of entertaining the class,” he told the Toronto Star. “I wasn’t the class clown, but always prominent — even when I was quiet.”

He said he was nearly expelled from boarding school and then dropped out of a military college after three days because he did not wish to subject himself to a buzz cut.

Mr. Trebek began working at the Canadian Broadcasting Corp. while studying philosophy at the University of Ottawa, where he graduated in 1961. As a broadcaster for radio and television, he delivered coverage in English and French, reported on news, weather and sports, and hosted “Reach for the Top,” a popular teen quiz show.

In 1973, Mr. Trebek came to the United States as host of “The Wizard of Odds,” a short-lived game show created by fellow Canadian Alan Thicke.

“It was canceled on a Friday, and I was disappointed, of course,” Mr. Trebek once said on “The Dan Patrick Show,” a sports talk program. “It was replaced the following Monday by a show called ‘High Rollers,’ which I also hosted. . . . After two and a half years, it was canceled, and it was replaced by another show which I hosted. So I have the either great honor or dubious honor of having replaced myself on three different occasions.”

Mr. Trebek, who became a U.S. citizen in 1998, also hosted shows including “Double Dare,” “The $128,000 Question” and “Battlestars.” He subbed for Chuck Woolery, Sajak’s predecessor on “Wheel of Fortune,” bringing him to the attention of Griffin. For a period Mr. Trebek hosted “Classic Concentration” and “To Tell the Truth” while also presiding over “Jeopardy!,” where he reportedly commanded $10 million a year.

As “Jeopardy!” host, Mr. Trebek participated in national contestant searches and shepherded the first teen, senior and celebrity tournaments. He also contributed clues, drawing from his knowledge in such arcane fields as oil drilling and bullfighting. He personally reviewed all clues before taping a show and claimed that he could answer about 65 percent of them correctly. If he judged one too difficult, he asked writers not to use it.

“I’ll say, ‘Nobody’s going to get this,’ ” he told the New York Times in a 2020 interview. “And they usually take my suggestions, because I view myself as every man.”

By the time Mr. Trebek completed 30 years as host, “Jeopardy!” reached 25 million viewers a week. His Emmys included a lifetime achievement award, and, in 2013, he ranked No. 8 in a Reader’s Digest poll of the most trusted people in America. Jimmy Carter, the highest-ranking president on the list, arrived at No. 24.

A ubiquitous presence in pop culture, Mr. Trebek appeared in the “Got milk?” advertising campaign, in films including “White Men Can’t Jump” (1992) and on television shows including “The Simpsons” and “The X-Files.” In a memorable episode of “Cheers,” Mr. Trebek welcomed as a contestant the postal carrier Cliff Clavin (John Ratzenberger), the sitcom’s most undesirable bachelor, in a round of “Jeopardy!” with categories including “beer,” “mothers and sons” and “celibacy.”

Mr. Trebek was spoofed on “Second City Television,” the Canadian TV sketch show, and “Saturday Night Live,” with comedian Will Ferrell, as his impersonator, barely containing his contempt for dimwitted contestants on “Celebrity Jeopardy!”

“I’ll take ‘Swords’ for $400,” Sean Connery, portrayed by Darrell Hammond, intoned in a Scottish accent when the category of clues was in fact “ ‘S’ Words.”

Mr. Trebek’s first marriage, to Elaine Callei, ended in divorce. In 1990, he married Jean Currivan. In addition to his wife, survivors include two children from his second marriage, Matthew Trebek and Emily Trebek; and a stepdaughter from his first marriage, Nicky Trebek.

Little changed about “Jeopardy!” as the years wore on for the show, for Mr. Trebek and for fans. Newfangled topics, such as twerking, were occasionally introduced. Over time, contestants revealed themselves to be more familiar with Dan Brown, author of “The Da Vinci Code,” than with the English poet Samuel Taylor Coleridge, the New Republic noted. And Mr. Trebek was called upon to learn to rap to read certain clues.

But mainly the show stayed “comfortable, like an old pair of shoes,” Mr. Trebek once said. In its constancy, it became all the more comforting for the legions of fans who turned to “Jeopardy!” for its promise of clear right and wrong answers in a world where the matter of what is true was increasingly subjected to partisan debate.

“There’s a certain comfort that comes from knowing a fact,” Mr. Trebek told the Times in July. “The sun is up in the sky. There’s nothing you can say that’s going to change that. You can’t say, ‘The sun’s not up there, there’s no sky.’ There is reality, and there’s nothing wrong with accepting reality. It’s when you try to distort reality, to maneuver it into accommodating your particular point of view, your particular bigotry, your particular whatever — that’s when you run into problems.”