Mnangagwa served for decades as Mugabe's enforcer, a role that gave him a reputation for being astute, ruthless and effective at manipulating the levers of power.
Among the population, he is more feared than popular, but he has strategically fostered a loyal support base within the military and security forces.
A leading government figure since Zimbabwe's independence in 1980, he is so widely known as the Crocodile that his supporters are called Team Lacoste for the brand's crocodile logo.
Mugabe unwittingly set in motion the events that led to his own downfall, firing his vice president on Nov. 6. Mnangagwa fled the country to avoid arrest while issuing a ringing statement saying he would return to lead Zimbabwe.
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"Let us bury our differences and rebuild a new and prosperous Zimbabwe, a country that is tolerant to divergent views, a country that respects opinions of others, a country that does note isolate itself from the rest of the world because of one stubborn individual who believes he is entitled to rule this country until death," he said in the Nov. 8 statement.
For weeks, Mnangagwa had been publicly demonized by Mugabe and his wife. Grace, so he had time to prepare his strategy. Within days of the vice president's dismissal, his supporters in the military put Mugabe and his wife under house arrest.
When Mugabe refused to resign, a massive demonstration Saturday brought thousands of people into the streets of the capital, Harare. It was not a spontaneous uprising. Thousands of professionally produced posters praising Mnangagwa and the military had been printed ahead of time.
"It was not a last-minute operation," Pigou said. "The demonstration was orchestrated."
In an interview with The Associated Press years ago, Mnangagwa was terse and stone-faced, backing up his reputation for saying little but acting decisively. Party insiders say that he can be charming and has friends of all colors.
Mnangagwa joined the fight against white minority rule in Rhodesia while still a teen in the 1960s. In 1963, he received military training in Egypt and China. As one of the earliest guerrilla fighters against Ian Smith's Rhodesian regime, he was captured, tortured and convicted of blowing up a locomotive in 1965.
While imprisoned, Mnangagwa studied through a correspondence school. After his release in 1975, he went to Zambia, where he completed a law degree and started practicing. Soon he went to newly independent Marxist Mozambique, where he became Mugabe's assistant and bodyguard.
In 1979, he accompanied Mugabe to the Lancaster House talks in London that led to the end of Rhodesia and the birth of Zimbabwe.
"Our relationship has over the years blossomed beyond that of master and servant to father and son," Mnangagwa wrote this month of his relationship with Mugabe.
In 1983, Mugabe launched a brutal campaign against Nkomo's supporters that became known as the Matabeleland massacres for the deaths of 10,000 to 20,000 Ndebele people in Zimbabwe's southern provinces.
Mnangagwa was widely blamed for planning the campaign of the army's North Korean-trained Fifth Brigade on their deadly mission into the Matabeleland provinces. Mnangagwa denies this.