The beloved host of 'Jeopardy!'? Who is Alex Trebek.

Alex Trebek, who presided over the beloved quiz show “Jeopardy!” for more than 35 years with dapper charm and a touch of schoolmaster strictness, died Sunday. He was 80.

Messages of condolences and respect from former contestants, celebrities, and the wider public quickly followed news of his passing.

“Alex wasn’t just the best ever at what he did. He was also a lovely and deeply decent man, and I’m grateful for every minute I got to spend with him,” tweeted “Jeopardy!” champion Ken Jennings. “Thinking today about his family and his Jeopardy! family – which, in a way, included millions of us.”

“It was one of the great privileges of my life to spend time with this courageous man while he fought the battle of his life. You will never be replaced in our hearts, Alex,” James Holzhauer, another “Jeopardy!” star, posted on Twitter.

John Legend tweeted that he was “obsessed with Jeopardy as a nerdy kid growing up in Ohio. I’ve loved and revered Alex Trebek since I can remember. What an iconic career.”

“We have lost an icon. Almost every night for more than three decades, Alex Trebek entertained and educated millions around the world, instilling in so many of us a love for trivia. My deepest condolences to his family, friends, and all who are mourning this tremendous loss,” wrote Canadian Prime Minister Justin Trudeau on Twitter.

“Jeopardy!” bills itself as “America’s favorite quiz show” and captivated the public with a unique format in which contestants were told the answers and had to provide the questions on a variety of subjects, including movies, politics, history, and popular culture.

They would answer by saying “What is ... ?” or “Who is .... ?”

The Canadian-born Mr. Trebek, who became its host in 1984, was a master of the format, engaging in friendly banter with contestants, appearing genuinely pleased when they answered correctly and, at the same time, moving the game along in a brisk no-nonsense fashion whenever people struggled for answers.

He never pretended to know the answers himself if he really didn’t, deferring to the show’s experts to decide whether a somewhat vague answer had come close enough to be counted as correct.

“I try not to take myself too seriously,” he told an interviewer in 2004. “I don’t want to come off as a pompous ass and indicate that I know everything when I don’t.”

The New York Times TV critic James Poniewozik wrote of Mr. Trebek:

“He had courtly formalities that are increasingly scarce in TV today. The “Shall we?” at the outset of a match. The little wince when someone would fumble a Double Jeopardy question. His Picard-like cool was his appeal, in an environment of emotive syndicated Kirks. When he delivered one of his trademark careful pronunciations – “Comintern,” “Argentina” – it seemed not showy but respectful. It was the spirit of “Jeopardy!” to care about getting things right.”

The show was the brainstorm of Julann Griffin, wife of the late talk show host-entrepreneur Merv Griffin, who said she suggested to him one day that he create a game show where people were given the answers.

“Jeopardy!” debuted on NBC in 1964 with Art Fleming as emcee and was an immediate hit. It lasted until 1975, then was revived in syndication with Mr. Trebek.

Long identified by a full head of hair and trim mustache (though in 2001 he startled viewers by shaving his mustache, “completely on a whim”), Mr. Trebek was more than qualified for the job, having started his game show career on “Reach for the Top” in his native country.

Moving to the United States in 1973, he appeared on “The Wizard of Odds,” “High Rollers,” “The $128,000 Question,” and “Double Dare.” Even during his run on “Jeopardy!”, Mr. Trebek worked on other shows. In the early 1990s, he was the host of three – “Jeopardy!”, “To Tell the Truth,” and “Classic Concentration.”

“Jeopardy!” made him famous. He won five Emmys as its host, including one last June, and received stars on both the Hollywood and Canadian walks of fame. In 2012, the show won a prestigious Peabody Award.

He taped his daily “Jeopardy!” shows at a frenetic pace, recording as many as 10 episodes (two weeks’ worth) in just two days. 

By 2008, the show had yet to bring in a substitute host for Mr. Trebek – save once, when he and “Wheel of Fortune” host Pat Sajak swapped their TV jobs as an April’s Fool prank.

In 2012, Mr. Trebek acknowledged that he was considering retirement, but had been urged by friends to stay on so he could reach 30 years on the show. He still loved the job, he declared: “What’s not to love? You have the security of a familiar environment, a familiar format, but you have the excitement of new clues and new contestants on every program. You can’t beat that!”

Although many viewers considered him one of the key reasons for the show’s success, Mr. Trebek himself insisted he was only there to keep things moving.

“I’m introduced as the host of ‘Jeopardy!’, not the star,” he said in a 2012 interview. “My job is to provide the atmosphere and assistance to the contestants to get them to perform at their very best,” he explained. “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,” he said.

In a January 2019 interview with The Associated Press, Mr. Trebek discussed his decision to keep going with “Jeopardy!”

“It’s not as if I’m overworked – we tape 46 days a year,” he said. But he acknowledged he would retire someday, if he lost his edge or the job was no longer fun, adding: “And it’s still fun.”

Mr. Trebek, who made a point of informing fans about his health directly, spoke in a calm, even tone as he revealed his illness and hope for a cure in a video posted March 6, 2019. But Mr. Trebek said he intended to fight it and keep working, even joking that he needed to beat the disease because his “Jeopardy!” contract ran for three more years. Less than a week later, he opened the show with a message acknowledging the outpouring of kind words and prayers he’d received.

“Thanks to the – believe it or not – hundreds of thousands of people who have sent in tweets, texts, emails, cards, and letters wishing me well,” Mr. Trebek said. “I’m a lucky guy.”

Born July 22, 1940, in Sudbury, Ontario, Canada, Mr. Trebek was sent off to boarding school by his Ukrainian father and French-Canadian mother when he was barely in his teens.

After graduating high school, he spent a summer in Cincinnati to be close to a girlfriend, then returned to Canada to attend college. After earning a philosophy degree from the University of Ottawa, he went to work for the Canadian Broadcasting Co., starting as a staff announcer and eventually becoming a radio and TV reporter.

He became a U.S. citizen in 1997. Mr. Trebek’s first marriage, to Elaine Callei, ended in divorce. In 1990, he married Jean Currivan, and they had two children, Emily and Matthew. Mr. Trebek lived with his family in Los Angeles’ Studio City section, not far from Hollywood.

Mr. Trebek is survived by his wife, their two children, and his stepdaughter, Nicky.

This story was reported by The Associated Press. The late AP entertainment correspondent Bob Thomas contributed to this report.