"The commander in chief of the Cuban revolution died at 22:29 hours" on November 25, the president announced on national television.
The former revolutionary leader will be cremated on November 26 in accordance with his wishes, Castro said.
The son of wealthy, Spanish-born landowners, Fidel Alejandro Castro Ruiz was born on August 13, 1926. He received a strict Roman Catholic education under Jesuit priests.
Their austerity may have influenced Castro, who said he was shocked by the stark contrast between his family’s wealth and the poverty of those around them.
Embracing Marxism-Leninism after law school in Havana, Castro in the early 1950s began organizing a militia in a bid to oust pro-American President Fulgenico Batista.
Under Batista's regime, known for its corruption and brutality, Havana was at the time a playground for America's rich -- famous for its nightlife and music.
But the fun ended on January 1, 1959. After failing six years previously in a bid to spark a popular revolt, Castro's forces finally ousted Batista, storming into Havana to the cheers of thousands of supporters.
Within days, Castro was doing a victory tour of the United States, as this newsreel of the time describes.
During the visit, which would be his last to the United States, Castro portrayed himself as a humble man without ambition.
Little did anyone know that he would go on to lead his nation for nearly half a century.
In the year following the revolution, relations between Havana and Washington soured. First, the United States suspended Cuban sugar imports after Havana nationalized a U.S.-owned oil refinery. Washington began a partial economic embargo of Cuba, followed by a severing of diplomatic ties.
But Castro was not to be deterred. Fortified by deepening political and economic ties with Moscow, Castro's forces soundly defeated a U.S.-backed invasion by Cuban exiles in the Bay of Pigs in April 1961.
Speaking at the United Nations, U.S. Ambassador Adlai Stevenson demanded to know from Valerian Zorin, his Soviet counterpart, whether Moscow was deploying nuclear-tipped missiles in Cuba that could hit U.S. cities.
"All right, sir, let me ask you one simple question," he said. "Do you, Ambassador Zorin, deny that the USSR has placed, and is placing, medium and intermediate range missiles in sites in Cuba? Yes or no? Don't wait for the translation! Yes or no!"
The answer was "yes," though Zorin refused to reply, much to Stevenson's chagrin.
Taped records of conversations involving U.S. President John Kennedy show that the world has perhaps never been closer to a nuclear confrontation.
But after a U.S. naval blockade of Cuba, Soviet leader Nikita Krushchev relented. The missiles were removed.
As America's No. 1 enemy, Castro was reportedly the target of hundreds of assassination attempts. One even reportedly included a cigar laced with explosives.
Castro went on to attain iconic status in Latin America, where Cuba's excellent medical system, 98 percent literacy rate, and low infant mortality were the region's best.
Yet progress came at a price, often paid by the Soviet Union, which at its demise in 1991 was giving Havana some $6 billion a year in aid.
With that money cut off, and the country still under an intense economic blockage, tens of thousands of Cubans sought to reach the United States aboard makeshift boats. Many of them died.
Cuba was fighting for survival, as Castro acknowledged in a 1992 speech when he said the country was being "asked again for an extraordinary international mission. Save the Cuban revolution! Save Socialism in Cuba!"
For now, that revolution is in the hands of Castro's younger brother, Raul, who was unanimously chosen as president by Cuba’s National Assembly in February, 2008.
Fidel Castro’s younger brother by four years, Raul had been acting president since 2006, when Fidel underwent intestinal surgery. Like Fidel, he was a revolutionary, serving as a rebel commander in the 1950s. After his brother became president, Raul rose to prominence in the regime. He was minister of the armed forces from 1959 to 2008.
As president, he has introduced economic reforms in the area of consumer choices, wages, and food production.