Umberto Eco, an Italian scholar in the arcane field of semiotics who became the author of best-selling novels, notably the blockbuster medieval mystery “The Name of the Rose,” died on Friday in Italy. He was 84.

His Italian publisher, Bompiani, confirmed his death, according to the Italian news agency ANSA. He died at his home in Milan, according to the Italian news website Il Post. No cause was given.

As a semiotician, Mr. Eco sought to interpret cultures through their signs and symbols — words, religious icons, banners, clothing, musical scores, even cartoons — and published more than 20 nonfiction books on these subjects while teaching at the University of Bologna, Europe’s oldest university.

But rather than segregate his academic life from his popular fiction, Mr. Eco infused his seven novels with many of his scholarly preoccupations.

In bridging these two worlds, he was never more successful than he was with “The Name of the Rose,” his first novel, which was originally published in Europe in 1980. It sold more than 10 million copies in about 30 languages. (A 1986 Hollywood adaptation directed by Jean-Jacques Annaud and starring Sean Connery received only a lukewarm reception.)

The book is set in a 14th-century Italian monastery where monks are being murdered by their co-religionists bent on concealing a long-lost philosophical treatise by Aristotle. Despite devoting whole chapters to discussions of Christian theology and heresies, Mr. Eco managed to enthrall a mass audience with the book, a rollicking detective thriller.

His subsequent novels — with protagonists like a clairvoyant crusader in the Middle Ages, a shipwrecked adventurer in the 1600s and a 19th-century physicist — also demanded that readers absorb heavy doses of semiotic ruminations along with compelling fictional tales.

In a 1995 interview with Vogue, Mr. Eco acknowledged that he was not an easy read. “People always ask me, ‘How is it that your novels, which are so difficult, have a certain success?’” he said. “I am offended by the question. It’s as if they asked a woman, ‘How can it be that men are interested in you?’” Then, with typical irony, Mr. Eco added, “I myself like easy books that put me to sleep immediately.”

While Mr. Eco had many defenders in academia and the literary world, critics in both realms sometimes dismissed him for lacking either scholarly gravitas or novelistic talent. “No cultural artifact is too lowly or trivial for Eco’s analysis,” Ian Thomson, a literary biographer, wrote in The Guardian in 1999 in a review of “Serendipities: Language and Lunacy,” Mr. Eco’s collection of essays on how false beliefs had changed history.

And the British novelist Salman Rushdie, in a scathing review in The London Observer, derided Mr. Eco’s 1988 novel, “Foucault’s Pendulum,” as “humorless, devoid of character, entirely free of anything resembling a credible spoken word, and mind-numbingly full of gobbledygook of all sorts.”

Appearing alongside Mr. Rushdie at a literary panel in New York in 2008, Mr. Eco wryly chose to read from “Foucault’s Pendulum.”

As a global superstar in both highbrow and popular cultural circles, Mr. Eco accepted such criticism with equanimity. “I’m not a fundamentalist, saying there’s no difference between Homer and Walt Disney,” he told a Guardian journalist who was exploring his juxtaposition of scholarship and pop iconography in 2002. “But Mickey Mouse can be perfect in the sense that a Japanese haiku is.”

Able to deliver lectures in five modern languages, as well as in Latin and classical Greek, Mr. Eco crisscrossed the Atlantic for academic conferences, book tours and celebrity cocktail parties. Impish, bearded and a chain-smoker, he enjoyed bantering over cheap wine with his students late into the night at taverns in Bologna.

He and his German-born wife, Renate Ramge, an architecture and arts teacher, kept apartments in Paris and Milan and a 17th-century manor once owned by the Jesuits in the hills near Rimini, on the Adriatic Sea. They had two children, Stefano, a television producer in Rome, and Carlotta, an architect in Milan.

Umberto Eco was born on Jan. 5, 1932, in Alessandria, an industrial town in the Piedmont region in northwest Italy. His father, Giulio, was an accountant at a metals firm; his mother, Giovanna, was an office worker there.

As a child, Umberto spent hours every day in his grandfather’s cellar, reading through the older man’s eclectic collection of Jules Verne, Marco Polo and Charles Darwin and adventure comics. During the dictatorship of Benito Mussolini, he remembered wearing a fascist uniform and winning first prize in a writing competition for young fascists.

After World War II, Mr. Eco joined a Catholic youth organization and rose to become its national leader. He resigned in 1954 during protests against the conservative policies of Pope Pius XII. But Mr. Eco maintained a strong attachment to the church, writing his 1956 doctoral thesis at the University of Turin on St. Thomas Aquinas.

He went on to teach philosophy and then semiotics at the University of Bologna. He also gained fame in Italy for his weekly columns on popular culture and politics for L’Espresso, the country’s leading magazine.

But it was the publication of “The Name of the Rose” that vaulted Mr. Eco to global renown. The monk-detective of the novel, William of Baskerville, was named after one of Sherlock Holmes’s cases, “The Hound of the Baskervilles.” The novel is narrated by a young novice who accompanies William through his investigation at the murder-prone monastery and acts as a medieval Doctor Watson.

In another literary allusion, this time to the blind Argentine writer Jorge Luis Borges, who set one of his stories in an encyclopedic library, Mr. Eco named the villain of the novel Jorge de Burgos and portrays him as the monastery’s blind librarian. De Burgos and his accomplices carry out their killings to prevent the disclosure of a supposedly lost Aristotle tome exalting the role of humor. The murderers believe the book is an instrument of Satan.

In “Foucault’s Pendulum,” his second novel, Mr. Eco tells the story of Léon Foucault, a French physicist in the 1800s who devised a mechanism to demonstrate the rotation of the Earth. Despite mixing allusions to the Kabbalah, mathematical formulas and Disney characters, the novel also became a worldwide best seller — even though it did not receive the near unanimous acclaim that critics had accorded to “The Name of the Rose.”

The pattern repeated itself with Mr. Eco’s other novels, which were often disparaged by critics but devoured by readers in spite of their dense prose and difficult concepts. Reviewing Mr. Eco’s fourth novel, “Baudolino” (2000), in The New York Times, Richard Bernstein wrote that it “will make you wonder how a storyteller as crafty as Mr. Eco ended up producing a novel so formulaic and cluttered as this one.”

Set amid the religious disputes and wars of the 12th century, “Baudolino” became the best-selling hardcover novel of all time in Germany and a commercial success elsewhere in the world.

Critics were kinder to Mr. Eco’s third novel, “The Island of the Day Before” (1994), in which an Italian nobleman, who cannot swim, survives on his shipwrecked vessel at a point in the tropical Pacific Ocean where the dateline divides one day from another.

“Eco has abandoned his familiar Middle Ages to create an extravagant celebration of the obsessions of the seventeenth century,” a reviewer in The New Yorker wrote, alluding to the author’s many anecdotes and explanations on the philosophy, politics and superstitions of Europe in that era.

Last fall, Houghton Mifflin Harcourt published a new Eco novel, “Numero Zero,” translated by Richard Dixon. The story, set in 1992, revolves around a ghostwriter who is pulled into an underworld of media politics and murder conspiracies, with a suggestion that Mussolini did not actually die in 1945 but lived in the shadows for decades. “This slender novel, which feels like a mere diversion compared with his more epic works, is nonetheless stuffed with ideas and energy,” John Williams wrote in The New York Times Book Review.

Mr. Eco received Italy’s highest literary award, the Premio Strega; was named a Chevalier de la Légion d’Honneur by the French government, and is an honorary member of the American Academy of Arts and Letters.

While he continued to make his scholarly peers uncomfortable with his pop culture celebrity, Mr. Eco saw no contradiction in his dual status. “I think of myself as a serious professor who, during the weekend, writes novels,” he said.