Jovanka Broz, who fought with Yugoslavia's anti-Nazi resistance movement during World War II, then married the country's communist dictator, Josip Broz Tito, died from cardiac arrest in a Belgrade hospital. She was 88.
Broz had been receiving care at the hospital since late August, said hospital director Zlatibor Loncar.
An ethnic Serb, Broz briefly met Tito, an ethnic Croat, during World War II while she fought as a marksman in the first female brigade of the Partisans. But it was not until she was assigned to work with the communist
leader after the war that their relationship developed.
The two married in 1952, and she was Tito's wife for nearly 30 years, but the couple did not have children.
"With Broz's death, we are left without one of the last most reliable witnesses of our former country's history,'' Prime Minister Ivica Dacic of Serbia said in a message of condolence.
Tito, who led the Partisan communist guerrilla group that fought the Nazi occupiers of Yugoslavia during the Second World War, took power in the nation after the conflict.
He ruled the multiethnic federation with a heavy hand, but also kept close relations with the West and gave Yugoslavia's citizens liberties such as free travel that were not allowed in other communist nations at the time.
Tito died in 1980, and Yugoslavia, a six-member federation, fell apart in early 1990s in a series of ethnic conflicts. Seven independent nations emerged after warfare that left 100,000 people dead and millions homeless
Over the next two decades, Broz accompanied Tito during his many international trips and at meetings with foreign leaders and celebrities, including British royals, US President Richard Nixon and Hollywood stars.
The couple started having problems and drifted apart in the 1970s.
After Tito's death, his successors accused Broz of ambitions to take over the country and placed her under house arrest.
Broz said she was kicked out of her residence, which was ransacked and her personal belongings impounded.
Later, as Tito's personality cult crumbled and his once-glorified role in Yugoslavia's history came under scrutiny, Broz mostly remained in isolation.
In a rare interview in 2001, she told the Blic newspaper that she lived in a Belgrade house without heating and often no electricity, and that she had no income or property to support herself.
"I'm totally deprived of any rights," Broz said at the time.
She did not hold valid Serbian identity documents until 2009, when a pro-democracy Serbian government moved to improve her status.
On Sunday, Serbian premier Dacic said in his message that "unfortunately the historic injustice has just started to be undone at the end of her life".
He said his government supported burying Broz at the same complex where Tito's tomb is located in a residential area of Belgrade.
Broz's funeral arrangements were not immediately announced.