They included the Nazi war criminal Klaus Barbie; the terrorist Ilich Ramírez Sánchez, a k a Carlos the Jackal; and Cambodia’s Khmer Rouge head of state, Khieu Samphan. Mr. Vergès also sought to defend the former presidents Saddam Hussein of Iraq, who was executed for crimes against humanity, and Slobodan Milosevic of Serbia, who represented himself in a war-crimes trial but died before a verdict.

Like many of his clients, Mr. Vergès, the son of a Vietnamese woman and a French diplomat, was an enigma. Assassins targeted him. There were hints of ties to secret services, to terrorists he defended and to Mao Zedong, Che Guevara and other revolutionaries. He was a confidant of Pol Pot, the tyrant blamed for the deaths of at least 1.7 million Cambodians. He married a terrorist he saved from the guillotine, but left her and his two children and disappeared for eight years.

“He’s a slippery man,” the director Barbet Schroeder, who made “Terror’s Advocate,” a 2007 documentary on Mr. Vergès and terrorism as a political weapon, told The New York Times in 2007. “You can never touch him. He loves the mystery. The reason is that there are certain things he cannot talk about. He would be in deep trouble if the truth came out.”

In a career that paralleled the postwar disintegration of colonial empires in Asia, Africa and the Middle East, Mr. Vergès rose to prominence in the late 1950s defending Algerians accused of terrorist bombings. Instead of contesting the evidence of French prosecutors in court, he insisted that the defendants were resistance fighters in a just war of liberation and challenged the legal and moral legitimacy of the trials.

While most of his clients were convicted, the trials drew international attention to Mr. Vergès, and long after Algerian independence in 1962 his tactics served as a blueprint for his cases, which became public platforms to indict France and other Western nations for what he called crimes of racist colonialism and the exploitation of third world peoples.