Aged 52, the first lady has become increasingly active in public life and in 2014 became the head the Zanu-PF party’s women’s wing.
Court politics are complex in Zimbabwe, but she is thought to be backed by “G-40”, a group of young activists of the under-40 generation that has earned a reputation for aggression.
She regularly attends rallies across the country, railing against anyone alleged to be disloyal to the president, and handing out clothes and domestic goods.
She told crowds in 2015 that she would put her husband in a wheelchair if necessary so he could run for re-election.
Grace was one of Mugabe’s secretaries when their affair began in 1987, and they had two children in secret before the president’s wife died in 1992.
The couple then married at a lavish ceremony in 1996 attended by Nelson Mandela.
She has often been accused of extravagant spending on luxury clothes and international travel, and of involvement in corrupt land deals.
Dubbed “Gucci Grace”, “The First Shopper”, or even “DisGrace”, she shown her political mettle in 2014 with her ruthless campaign against then Vice President Joice Mujuru, who was then a contender to succeed her husband.
She launched sustained verbal attacks against Mujuru, accusing her of corruption and plotting to topple the president.
Soon afterwards, Mujuru, a former guerrilla fighter who had held cabinet posts in every Mugabe government since independence in 1980, was ousted from the party leadership and later from ZANU-PF.
‘I don’t even care’
Born on July 23, 1965, in South Africa, Grace Marufu has three children with Mugabe, 41 years her senior, as well as a son from her first marriage.
She has a short temper – perhaps in evidence last weekend when she allegedly assaulted a model who was at a Johannesburg hotel with her two sons.
In 2009, she punched a British photographer in Hong Kong for taking pictures of her at a luxury hotel.
But she told a South African Broadcasting Corporation programme that she is no longer concerned about what people think of her.
“I have developed a thick skin, I don’t even care,” she said. “My husband says ignorance is bliss.”
Nonetheless there have been efforts to change public perceptions, with her supporters showering her with new nicknames – such as “Dr Amai (Doctor Mother)”, “unifier” and “queen of queens”.
Grace was also awarded a doctorate by the University of Zimbabwe, where her husband is chancellor, reportedly just three months after enrolling.
But political analyst Earnest Mudzengi said Grace Mugabe lacks popular appeal and has stirred disharmony in Zanu-PF.
“She was literally hand-picked. She has created enemies and enemies are being created as we speak, just look at the purges in Zanu-PF,” Mudzengi said.
“She does not have popular support and does not fit in the framework of how Zanu-PF leaders are chosen. Normally they would require that someone must have liberation war credentials or that they must have worked tirelessly for the party.”
Analysts suggest she may not want the top job herself but is positioning her family to try to ensure protection and support in the dangerous years after the president dies.