The official guest list goes on for 20 pages, with a varied group of VIPs such as former Spanish King Juan Carlos I, a vice president of the North Korean worker's party and left-leaning actor Danny Glover.
Castro's wife and children, whose existence for years was a state secret, could make a rare appearance. Castro's long-estranged sister Juanita Castro said she would not be leaving exile in Miami to attend the funeral.
Nearly every Latin American head of state will be on hand, though.
The arrival of left-leaning presidents of Bolivia, Ecuador, Nicaragua and Venezuela is no surprise and in fact speaks to how much the world has changed since Fidel Castro took power in 1959.
Shortly after the Cuban revolution, every country in the Western Hemisphere except Mexico broke relations with Cuba, alarmed at Castro's growing alliance with the Soviet Union.
But thanks to a recent boom in leftist governments -- some Castro helped to install, like that of Nicaragua's Daniel Ortega -- the region is now chock-full of Cuba allies.
Many observers will be watching for the interaction between Venezuelan President Nicolas Maduro and Raul Castro. Since late Venezuelan President Hugo Chavez began to copy Cuba's socialist and fiercely anti-US government style, Cuba and Venezuela have all but melded into one country.
But with oil prices plummeting, Venezuela has been forced to cut precious oil subsidies to Cuba, leading many to wonder if the Venezuela-Cuba love affair is on the rocks.
Both Colombian government officials and their longtime adversaries the FARC guerrillas are attending. That speaks volumes about how Cuba has changed its role in world affairs.
For decades, Cuba supported the Marxist guerrillas in their attempt to topple Colombia's government, earning the island until 2015 a spot on the US State Department's list of countries that support terrorism.
But for the last four years Cuba hosted Colombian peace talks that in November led to a deal between Colombia's government and guerrillas
, a big turnaround from the early years, when an isolated Fidel Castro tried to spread his revolution to other countries at the point of a gun.
For decades Cuba was a beacon for would-be revolutionaries and even provided military training to dozens of radical groups, who are sending representatives to pay their respects to the fallen Castro.
CNN's Nic Robertson caught up with Gerry Adams, the former leader of Sinn Fein, the political wing of the IRA, as he stood in the massive line of people in Havana's Revolution Square
"I'm here because Fidel was a good friend to Ireland," Adams said.
Castro was also "a good friend" to revolutions across Africa. On Tuesday, Zimbabwe's ailing President Robert Mugabe arrived to attend the memorial to Castro.
"Fidel wasn't just your leader, Fidel was the leader of all revolutionaries," Mugabe told Cuban state TV upon arriving at Havana's Jose Martí Airport.
But leaders of the United States and Russia, the two countries that most defined Cuba's international relations, will be conspicuously absent during the memorials.
Despite having made history by restoring diplomatic relations with Cuba and carrying out the first visit to Cuba since the revolution by a US president, Barack Obama will skip Castro's funeral.
Obama did not meet with Castro during his landmark trip and the former Cuban leader later attacked him for his Cuba policy.
The US Embassy in Havana is one of the few diplomatic missions in the Cuban capital that has not lowered its flag to half-staff to mark Castro's death.
President-elect Trump has slammed Obama's policy and promised a tougher line on Cuba
"If Cuba is unwilling to make a better deal for the Cuban people, the Cuban/American people and the US as a whole, I will terminate deal," Trump tweeted on Sunday.
While Russia is sending a delegation to Cuba, Vladimir Putin, who met with Castro during his last visit to Cuba in 2015 and promised closer relations with the former USSR's close ally, is not scheduled to travel to the island.
There has been no explanation for Putin's absence, but it may well be that the Russian President is prioritizing the possibility of better relations with the incoming Trump administration over Russia's past ties with an old comrade.