His death was announced by the current Italian president, Sergio Mattarella. The cause was not immediately available.
In the years since the end of World War II, Italians have seen dozens of governments rise and fall, the state of their politics often subjected to gentle ribbing if not outright mockery on the international stage.
Amid that chaos, Mr. Napolitano, a onetime leader of the Italian Communist Party who later embraced the tenets of social democracy and European integration, emerged as a person of undisputed seriousness, the definition of an elder statesman.
When the country’s often warring political factions could agree on little or nothing else, they found accord on Mr. Napolitano, who had spent decades in Parliament and had held office as interior minister.
Mr. Napolitano was elected to his first seven-year term as president in 2006, at age 80. When the parliament deadlocked on the selection of a successor, he became the first Italian president elected to a second term and served a total of nearly nine years before he retired in 2015.
With its seat at the Quirinale palace in Rome, the Italian presidency is often regarded as a ceremonial office. But Mr. Napolitano demonstrated that with political savvy and personal gravitas, it could be used to substantial power.
He was credited with leading the country through one of its most severe crises of the modern era in 2011, when Berlusconi, the scandal-plagued billionaire media tycoon who for years had been the dominant figure in Italian politics, stepped down amid a debt crisis.
Mr. Napolitano ushered in a new prime minister, economist Mario Monti, and a technocratic government of experts.
“Now is the time to show maximum responsibility. It is not the time to pay off old scores nor for sterile partisan recriminations,” the New York Times quoted Mr. Napolitano as saying at the time. “It is time to reestablish a climate of calmness and mutual respect.”
The Monti government, while short-lived like those that came before and after it, was widely credited with steadying the country’s economy. Monti was succeeded by prime ministers Enrico Letta and then Matteo Renzi before Mr. Napolitano’s retirement. By then, he was known admiringly in some circles as “Re Giorgio” — King Giorgio.
Giorgio Napolitano was born in Naples on June 29, 1925, three years after the fascist leader Benito Mussolini rose to power. Mr. Napolitano’s mother was of noble heritage. His father was a lawyer, a path that Mr. Napolitano followed as he pursued his studies at the University of Naples.
An anti-fascist, Mr. Napolitano joined the Italian Communist Party and was first elected to the Chamber of Deputies, the lower house of the Italian parliament, in 1953.
Such was his commitment to the Communist cause that he supported the Soviet quashing of the 1956 Hungarian Revolution. But by the following decade, he had begun to turn against Moscow, the Times reported in a profile. He spoke out against the brutal Soviet response to the Prague Spring movement in 1968.
Mr. Napolitano eventually left the Communist Party, helping to form the Democrats of the Left. He served as speaker of the Chamber of Deputies and as interior minister under Prime Minister Romano Prodi in the 1990s.
Mr. Napolitano was married in 1959 to Clio Maria Bittoni, a lawyer. Besides his wife, survivors include two sons, Giovanni and Giulio. A complete list of survivors was not immediately available.
By the end of his time on the public stage, Mr. Napolitano had been named a senator for life, one of his country’s highest honors. But in his earlier days as a moderate Communist, was a man in the middle, enjoying the full trust neither of his fellow party members nor of the West.
At one point, Mr. Napolitano was denied a visa to visit the United States because of his Communist Party membership. In an editorial on the matter, The Washington Post described him as “a man of considerable intellectual distinction” and observed that “to bar him on grounds that he constitutes a menace to the republic … is ludicrous.”
Mr. Napolitano was ultimately permitted to visit the United States. Henry A. Kissinger, the former secretary of state and national security adviser, was said to have called him his “favorite Communist.”
