S.I. Newhouse, the Conde Nast chairman who presided over the magazine world’s glossiest publications and most talked-about editors for more than 40 years, died Sunday. He was 89.

Newhouse’s death was confirmed early Sunday by a family spokesman, according to a report on the website of Vogue, one of the cornerstones of the Newhouse family’s publishing empire.

SI Newhouse was the most extraordinary leader,” said Anna Wintour, Conde Nast Artistic Director and Editor-in-Chief of Vogue. “Wherever he led, we followed, unquestioningly, simply because he put the most incredible faith in us. SI never looked at data, or statistics, but went with his instincts, and expected us to do the same. He was quick to encourage us to take risks, and effusive in his praise when they paid off. There was nothing showy about the way SI led though. This humble, thoughtful, idiosyncratic man, possibly the least judgmental person I have ever known, preferred family, friends, art, movies, and his beloved pugs over the flashiness of the New York media world, and his personality shaped the entire company; it might have been a huge global entity, yet one felt a deep, personal connection to it, all because of him.”

Even as the magazine business suffered declines in the digital age, Newhouse spent lavishly on Conde Nast’s gold-plated roster of titles that include Vogue, the New Yorker, Vanity Fair, Glamour, Wired, Architectural Digest, Details, Self, GQ and Bon Appetit. He had a knack for picking strong editors with the vision to ensure Conde Nast’s publications stood out from the pack — personalities who inevitably became celebrities in their own right. Anna Wintour, Graydon Carter, Tina Brown, David Remnick, Ruth Whitney and Diana Vreeland were among the stars in the Conde Nast orbit during Newhouse’s long tenure.

“Today, we lost a giant,” said Bob Sauerberg, president and CEO, Conde Nast. “Si embodied creativity, curiosity and a commitment to excellence unlike any other, and he will forever be remembered as the man who built the most influential media empire in the world. We are honored to work in this incredible business he created, and will strive to emulate his courage and wisdom.”

By many accounts, Newhouse was soft-spoken and unimposing, a diminutive man who was prone to wearing casual clothing around the office. He shied away from the limelight, preferring to let his magazines and his editors take the bow. But he was a fixture on the New York social scene, a bon vivant who loved the influence exerted on pop culture and high society by his stable of publications. He was known for his prized extensive art collection that adorned the walls of his New York City penthouse.

“Si Newhouse wasn’t incidentally in the magazine business,” said Remnick. “He loved magazines, he loved everything about them––from the conception of new publications to the beauty and rigor of the latest issue––and that passion, that commitment to excellence, free expression, and imagination radiated in every direction.”

In addition to overseeing Conde Nast, Newhouse served as chairman of Conde Nast parent company Advance Publications, a holding company for the Newhouse family media empire. The list includes 26 newspapers, including Newark, N.J.’s Star-Ledger, Cleveland’s Plain Dealer and Portland, Ore.’s Oregonian; the Parade magazine Sunday insert; a 25% stake in Discovery Communications; and substantial cable TV holdings.

In March 2015 Advance reached a deal with Charter Communications to sell Bright House Networks, the nation’s sixth-largest cable operator with 2.2 million subscribers, for $10.4 billion as part of Charter’s acquisition of Time Warner Cable. The deal brought the Newhouse clan about $2 billion in cash and a 13%-14% stake in the enlarged Charter Communications.

Born in New York City, Samuel Irving Newhouse Jr. was the scion of the Newhouse empire who dropped out of college and proved to be a late bloomer in his professional life. His father, Samuel Newhouse Sr., was a self-made publishing mogul who built up his newspaper holdings after starting out as a copyboy as a teenager at a New Jersey. He famously bought the Conde Nast magazine group in 1959 as a gift for his wife, Mitzi, who was a reader of Vogue. Samuel Newhouse Sr. died in 1979.

S.I. (or Si) eventually gravitated to the Conde Nast magazines while his younger brother, Donald, took charge of the newspapers. It was reportedly a truism in Newhouse family circles that when it came to business, “Donald makes the money; S.I. spends it.” The net worth of the Newhouse brothers was estimated by Forbes in August 2015 at $8.3 billion apiece.

Advance Publications also invested in TV stations in the 1950s and ’60s but sold those holdings in 1980 to buy into the burgeoning cable business. Advance/Newhouse Communications, the Syracuse, N.Y.-based cable unit, was headed by Robert Miron, a cousin of S.I. and Donald who is a respected cable TV pioneer.

S.I. Newhouse’s approach to running magazines was greatly influenced by his admiration for the aesthetic tone set by of Alexander Liberman, the legendary editorial director of Conde Nast from 1960 to 1991. Newhouse, who was named chairman of Conde Nast in 1975, was known for empowering his editors and backing them unfailingly — unless he lost faith in their vision or leadership qualities; if circumstances warranted, he was quick to make changes.

Conde Nast enjoyed solid growth throughout the 1980s and ’90s under Newhouse’s leadership. The 1979 launch of Self magazine, designed as a hipper and smarter version of a woman’s magazine, proved an early success. The same year, the company acquired GQ and gradually revived what had become a moribund brand.

“With Si’s passing, the big chapters in the history of magazines—as written by men like Si and Henry Luce—will have come to an end,” said Carter. “Si’s vision, and the soft manner in which he executed it, will be long remembered in these hallways and on newsstands around the world. He was a one-off in an age of carbon copies.”

In 1983 Conde Nast decided to revive a storied title that had become a casualty 50 years earlier of the Great Depression. The relaunch of Vanity Fair was rocky until Tina Brown, who had made a mark as an editor in her native England, was recruited to take the reins in 1984. The magazine famously has a lifetime contract with noted photographer Annie Liebowitz. The publication’s annual Oscar night party, inaugurated in 1994, is another examples of Conde Nast’s largess. Carter has held the reins of Vanity Fair since 1992, since Brown was dispatched to the New Yorker, the venerable weekly that was rescued from financial troubles by Conde Nast in 1985. Newhouse suffered through 18 years of red ink before the publication turned the corner under current editor David Remnick. Carter recently announced his decision to end his tenure at Vanity Fair in December.

Other acquisitions under Newhouse included Bon Appetit and Architectural Digest in 1993, Wired in 1998 and Fairchild Publications, parent company of fashion bible Women’s Wear Daily in 1999. (The bulk of Fairchild Media assets were purchased in 2014 by Penske Media Corporation, parent company of Variety.)

One of the most high-profile stumbles in Newhouse’s career was the short-lived Portfolio magazine, an effort to add a business-oriented magazine to the stable. The monthly startup reportedly churned through $100 million and shuttered, after just two years, in 2009, as worldwide advertising spending took a dive in the global recession.

Given Newhouse’s advancing years, a management transition began at Conde Nast in 2004 when Charles Townsend, former Glamour publisher and Conde Nast COO, was named CEO.

Newhouse’s survivors include his wife, Victoria; his brother Donald; two children, Pamela and Sam, by his first marriage to Jane Franke; and five grandchildren.