Under his leadership, the small country of 11 million became a major player in modern 20th century politics because of Castro's disagreements with the United States and alliances with Soviet leaders, while situated in proximity to Florida shores.
"He was always a polarizing figure," said Jorge Dominguez, an expert on Cuba at Harvard University. "He was well aware that some thought he was a hero while others thought he was demon."
Here’s a look at Castro’s controversial legacy in Cuba.
In 1934, General Fugencio Batista rose to power through a U.S.-assisted coup. He was first elected president and later became a dictator who was widely maligned for Cuba’s income disparities, including high unemployment and poverty, at the same time as casinos were built to attract wealthy American tourists.
In 1959, at the age of 32, Castro led a small rebel army, launching a guerilla war to overthrow Batista and execute some of his supporters.
President Eisenhower and the American government cautiously approached the change of hands in the Cuban government. Soon after Castro assumed power, relations between the neighboring countries deteriorated.
In 1961, President Eisenhower formally enacted a trade embargo with Cuba as Castro nationalized oil refineries and agricultural companies because they would not share profits with Cubans. He turned to the Soviet Union for help.
Castro claimed that three U.S. presidents —- Eisenhower, Kennedy, and Johnson —- tried to assassinate him. He also boasted that he was able to foil over 600 attempts by the CIA, though the U.S. has not confirmed those claims.
In 1975, the United States Senate Select Committee to Study Governmental Operations with Respect to Intelligence Activities, or the "Church Committee," found "concrete evidence of at least eight plots involving the CIA to assassinate Fidel Castro from 1960 to 1965."
Castro saw the United States as the enemy and his fight against democracy as his calling. "I realized that my true destiny would be the war that I was going to have with the United States" he said in a documentary about his life.
"Castro’s greatest legacy will be taking a small Caribbean island and transforming it into a major actor on the world stage compared to its geographic size," said Peter Kornbluh, a Senior Analyst at the National Security Archive and expert on Cuba. "Cuba became the most legendary David vs. Goliath story in contemporary history, subduing efforts for the United States to eliminate him."
But for thousands of people seeking refuge from Castro’s Communist regime, which had adopted many of the restrictions of the Soviet "iron curtain," the United States was seen as a place of promise and hope.
Over the course of Castro’s rule, hundreds of thousands would risk their lives to travel across the 90-mile span of ocean, by any means necessary, for the U.S. Many Cuban exiles settled across southern Florida.
The first mass wave of refugees came in 1961 during Operation Pedro Pan, in which 14,000 young children were voluntarily separated from their parents and brought to the United States by the CIA and Catholic Church.
Despite condemning United States policy, Castro met with Vice President Richard Nixon, Former President Jimmy Carter and President Bill Clinton.
In 2014, President Barack Obama and Castro’s brother, Raúl, who had become president of Cuba in 2008, announced negotiations toward thawing relations between the two countries, with the assistance of the Vatican and Canada. Fifty-three political prisoners were released from Cuban custody, along with an unnamed American CIA operative and U.S. government contractor Alan Gross. The U.S. released three members of the Cuban 5 - political prisoners accused of spying in the U.S.
In 2016, Obama became the first sitting United States president to visit Cuba since 1928. The Cuban government established an embassy in Washington, D.C. and the U.S. government established one in Havana in 2015. American travel restrictions to Cuba have been relaxed and the rules of the trade have been somewhat eased.
Castro remained a critic of his brother’s moves to renew ties with the U.S. He wrote an article in the state-run Cuban newspaper, Granma, against what he called American imperialism and continued to be critical after Obama's visit to Cuba.
But relations are still limited and President-elect Donald Trump said during his campaign that he would reverse Obama’s executive orders normalizing relations with Cuba. Trump has also said he would consider trade negotiations, in the interest of business, if he can "get a better deal" for the U.S. that would include the release of political prisoners.
In a January 1967 interview with Playboy magazine, Castro admitted there were 20,000 "counter-revolutionary criminals" in Cuba’s prisons.
"Cuba had a horrendous record of human rights violations in the 1960s and there are arbitrary arrests for speaking out. There is also very limited freedom of speech," said Professor Phillip Brenner, an expert on Cuba at American University.
Under his dictatorship, Castro arrested dissidents and gay citizens and forced them into labor or prison, according to human rights groups. He is also responsible for mass executions of people who spoke out against his government.
"Over more than five decades documenting the state of human rights in Cuba, Amnesty International has recorded a relentless campaign against those who dare to speak out against the Cuban government’s policies and practices," the organization said in a statement following Castro’s death.
"As other countries in the region turned away from authoritarian rule, only Fidel Castro’s Cuba continued to repress virtually all civil and political rights," said José Miguel Vivanco, Americas director at Human Rights Watch. "Castro’s draconian rule and the harsh punishments he meted out to dissidents kept his repressive system rooted firmly in place for decades."
Castro’s government has also discouraged dissidents by the use of threats and surveillance. Cubans feared for their safety if they spoke out against his Communist regime and the country has prevented non-profits and rights organizations from entering and monitoring human rights.
After the United States announced it was normalizing diplomatic relations with Cuba, 53 political prisoners were released, though there are many remaining according to human rights groups.
Cubans receive services that rights groups deem essential and have had more of a voice on the internet in recent years.
"People are not arrested for having blogs on the [Cuban controlled] 'intranet' and people have access to television that is widely used," Vivanco added, noting that "the Universal Declaration of Human Rights has many provisions that Cuba provides, like healthcare and education."
In Africa, Castro is seen as a champion of equality because he sent doctors, troops, and teachers to impoverished post-colonial countries. He sent thousands of troops to fight with opposition forces to the then-apartheid governments of Angola and Namibia. After Nelson Mandela was released from prison, he traveled to Cuba to thank Castro for his support.
Following Castro’s death, some of the most emotional eulogies came from African leaders who praised his efforts across the continent.
School attendance is mandatory through secondary education. Hence, according to the United Nations, Cuba’s population has a literacy rate of 99.8 percent, one of the highest in Latin America. Castro enacted the Campaña Nacional de Alfabetización en Cuba (Cuba Literacy Campaign) to bring teachers to rural areas that previously did not have as much education.
The Cuban government said it believed educated citizens would aid the country’s new society, but critics have argued that the compulsory education was a form of brainwashing —- an opportunity for the Communist party to indoctrinate young children.
Life expectancy in Cuba is high and infant mortality rates are low, according to UNICEF. At 5.8 infant deaths per 1,000 births, Cuba’s infant mortality rate is among the lowest in the world; it’s lower than that of the United States at 6.2. Life expectancy among men and women are 77 and 81 years, respectively. The country has a relatively high number of physicians –- eight for every 1,000 patients -- almost double the rate in the United States.
But, the facilities in most hospitals are out of date and lack the medical technology found in most developed countries, as well as many basic medicines.
Following the collapse of the Soviet Union, subsidies that were used to prop up Cuba’s government, healthcare, and education systems in 1991 disappeared, a time known as the "special period."
Cuba blames the U.S. government's embargo for their lack of access the latest medicines, many of which are produced and developed in the United States.
Physicians trained in Cuba are considered well trained and an "export" for the country, recognized by the UN and WHO for their skill and Cuba’s willingness to send them to help with health crises abroad like the Ebola outbreak in West Africa.
Medical research in Cuba has been recognized around the world and new research exchanges between Cuba and the U.S. have opened. Currently, the first U.S. trial of a lung cancer therapy, which triggers the body's immune system to fight the cancer, has been planned by the Roswell Cancer Institute in Buffalo, New York.
In 1960, after Castro was in power, the United States canceled sugar imports from Cuba and ceased exporting oil. In turn, Cuba nationalized the American-owned oil companies still in the country. The United States placed a trade embargo on exports to Cuba with the exception of food or medicine.
Castro turned to Communist allies and developed diplomatic relations with the Soviet Union's Nikita Kruschev, who agreed to prop up the tiny Communist Caribbean island's economy in exchange for troops and its only crop, sugar. In return, Cuba received oil which it was able to trade across Latin America.
Following the collapse of the Soviet Union in 1991, Cuba's already weak economy went into a steep decline. It later found a friend in Hugo Chavez and the oil rich country of Venezuela. But when Venezuela's economy went into a tailspin and was marred by corruption and scandals, Cuba was forced to look inward.
The government began to consider some economic opportunities for citizens not run by the state during the "special period."
The Cuban government has also improved internet access, though it remains prohibitively expensive for most Cubans.
But most economic activity is still directed by the government and today wages for Cuban citizens are unsustainable -- the average Cuban makes around $25 a month, according to the Cuban government. Although the government pays for housing, education, healthcare and a portion of their food, that amount of income leaves most citizens of the country dependent upon money from family in the U.S., referred to as remittances, and second jobs in the expanding private sector.
As relations have begun to ease, under Raul Castro, and tourism is on the rise, Cuban people say they are seeing a rise in income and hope that the economy will improve.
"I have personally observed and experienced the changes that have occurred on the island since 2014, and they are material," said Scott Gilbert, a legal and Cuba relations expert.
"They include hugely increased internet and information flow, the circulatory system of a democracy," Gilbert added. "There also is a pronounced increase in privately-owned businesses, and a huge increase in candid public dialogue everywhere about the government and the future. Previously, people were very circumspect in talking, if at all, about these subjects."