Mira Markovic, the widow of former Yugoslav president Slobodan Milosevic, died in Russia at the age of 76.
Her death was confirmed to the BBC by Milutin Mrkonjic, a close friend of the family.
Ms. Markovic, known as "Lady Macbeth of the Balkans", was a significant political figure during the collapse of Yugoslavia in the 1990s.
She was one of her husband's most trusted and influential advisers before he was arrested in 2001 and fled to Russia two years later.
Milosevic died in 2006 while being held at the UN War Crimes Tribunal in the Netherlands. He had been charged with genocide and other war crimes for his key role in the 1990s wars that had torn the Balkans apart.
- Mira Markovic: Power behind Milosevic
They had been married for four decades and were almost inseparable until Milosevic's extradition.
Ms. Markovic owed her political influence as the closest confidant, but she also had her own political party, the neo-communist Yugoslav United Left (JUL).
Before meeting her husband, Ms. Markovic had a nagging childhood. Her mother was a partisan fighter captured by the Nazis in 1942.
Under torture, she apparently revealed secrets. A report suggests that her own father – the grandfather of Ms. Markovic – ordered the execution of his daughter for treason after her release.
Ms. Markovic escaped from Serbia in 2003, where she was charged with abuse of power and suspected of cigarette smuggling and political assassination.
Brought together by tragic family stories
By Aleksandra Niksic, BBC News Serbian Editor
Markovic and Milosevic met in Milosevic's hometown Pozarevac as childhood friends and married in 1965. Those who knew them often said that the couple shared tragic family stories with each other. Both parents of Milosevic committed suicide, while Markovic's mother was estranged due to political differences during the Second World War.
They had two children – daughter Marija and son Marko, who lived with Markovic in Russia. Daughter Marija Milosevic was estranged from the family after her father's death in 2006 and lived in neighboring Montenegro.
Serbian opposition parties called her "Red Witch" because of her political stance. She fled to Russia after the Serbian judiciary started investigating corruption cases, as well as threats and murders of journalists and political opponents of the couple.
Milosevic's brother Borislav, once ambassador to Moscow, allegedly organized the move and asylum for her and her son Marko.