Jimmy Neary, an Irish immigrant who boarded a ship to America in the 1950s and went on to open a namesake East Side pub and restaurant in Manhattan that for more than a half century has been a canteen for the city’s power brokers, died on Oct. 1 at his home in Manhattan. He was 91.

His daughter Una Neary confirmed the death.

With Neary’s, which opened on St. Patrick’s Day in 1967, Mr. Neary ran the kind of fabled establishment that people now say is part of a vanishing New York.

There, diners sit at red leather banquettes in a room of red tablecloths to eat hearty fare like lamb chops with mint jelly. A dress code forbids T-shirts and shorts, and the walls are lined with pictures of famous customers, like Ted Kennedy, Michael Bloomberg, Rudolph Giuliani and Kathie Lee Gifford.

Sure, the regulars came for the restaurant’s corned beef and cabbage, but they also came because of Jimmy Neary. Spry, diminutive and white haired, he was, to some, their “favorite leprechaun” as he roamed the restaurant spreading hospitality with a lilting Irish brogue.He didn’t drink himself, always wore a suit and favored Kelly green and American flag neckties. He closed Neary’s only once a year, on Christmas Day.

Mr. Neary would awake at dawn and begin his mornings watching Fox News and a televised Mass or two. Before driving to work from New Jersey, he would often pray at church and visit the grave of his wife, Eileen. His car’s license plate noted his Irish county of origin: “Sligo.”

When he opened the restaurant, on 57th Street near First Avenue, the city was teeming with traditional Irish-run saloons, and Neary’s was more like one of them. But that changed when Gov. Hugh Carey, who liked the smoked salmon on the menu, became a regular. Word got around and a high-powered clientele began showing up.

Neary’s habitués have included Mayor Ed Koch, the New York City police commissioners Ray Kelly and Bill Bratton, Cardinal Timothy M. Dolan, George Steinbrenner, Roger Ailes, Jimmy Breslin, Gay Talese and Maureen O’Hara.

When the city’s movers and shakers gathered at his restaurant, Mr. Neary said, he’d reflect on how far he’d come from the farm fields of his Sligo childhood.

“Sometimes I think, ‘Am I dreaming?’” he said in the sports photographer Neil Leifer’s 2017 documentary film, “Neary’s: The Dream at the End of the Rainbow.” “Because of the people that have walked through this door.”

Mary Higgins Clark, another Neary’s regular, wrote Mr. Neary into many of her suspense novels, including one where he helps solve a murder. He claimed never to have read them (“I’m not a reader,” he explained), but he framed their covers by the bar.

Timothy Mara, co-owner of the football Giants, gave Mr. Neary two Super Bowl rings, which went on display at the restaurant.

Mr. Bloomberg always celebrated New Year’s Eve with a bash at Neary’s.

“I first started going to Neary’s 40 years ago, when I lived in an apartment around the corner,” Mr. Bloomberg said in a statement to The New York Times. “Some people went to eat, some went to drink, but most of us went to see Jimmy.”

When Mr. Bloomberg, as mayor of New York, went to County Sligo in 2006 to dedicate a monument to the Fighting 69th, a storied New York Army regiment of Irish heritage, he invited Mr. Neary to join him on his private jet. After the ceremony, the mayor surprised him by taking him to Mr. Neary’s hometown, Tubbercurry.

As SUVs swarmed into the village, people stepped out of shops and pubs to see what the fuss was about. They realized soon enough: Jimmy Neary was back home, and he was getting out of a car with the mayor of New York.

James Joseph Neary was born in Tubbercurry on Sept. 14, 1930. His father, Patrick, was a police officer and a farmer. His mother, Catherine (Marren) Neary, was a homemaker.

At school they poked fun at Jimmy for his size. But he later got the last laugh when he cleaned out everyone’s pockets at a poker game. With his winnings he bought two lambs, which he bred into more lambs, which he then sold. At 24, he purchased an ocean liner ticket to America with the earnings.

“You’re so small,” he recounted his mother telling him. “What are you going to do in America?”

“I have no idea, mum,” he said. “But I’m on my way.”

Arriving in Manhattan, Mr. Neary was greeted at the pier by his older brother, John, a police officer who had immigrated earlier. Jimmy soon found a job as a porter at the New York Athletic Club and a place to live in the Bronx. Drafted into the Army, he learned how to drive a tank at Fort Hood in Texas before being deployed to Germany. After his service, back in New York, he tended bar at P.J. Moriarty’s for years.

Mr. Neary was pouring pints one evening when he met Eileen Twomey, whom he married in 1966. The next year, he opened Neary’s with a fellow bartender, Brian Mulligan, who remained his partner until he died in the mid-1980s.

Around that time Mr. Neary bought the building housing the restaurant — a purchase that served him well decades later when the coronavirus pandemic gripped New York. As other businesses closed because they couldn’t make rent, Neary’s stayed afloat. His daughter Una, who worked for her father as a waitress in her younger years and then helped him run the place while holding down her day job in finance, will continue to oversee the business.

In addition to her, Mr. Neary is survived by two other daughters, Ann Marie Bergwall and Eileen Bowers; his son, Patrick; and eight grandchildren.

Over time, Mr. Neary’s regulars became something like family to him as well. But every once in a while, Una Neary said, an unfamiliar face would walk into the restaurant and approach the bar, somewhat hesitantly, and invoke his Gaelic name.

“Is Séamus Neary here?” the visitor would ask. “I used to know him back in Ireland long ago before he was famous.”