She is known for deft political maneuvering, a volcanic temper and a reputation for corruption.

She once punched a photographer in Hong Kong with a diamond-encrusted fist.

More recently, she was whisked out of South Africa to avoid arrest after a fashion model accused her of beating her with an electrical cord.

As Zimbabweans have been mired in poverty under President Robert Mugabe, Africa’s longest-serving leader, his wife, Grace, 52, became a target of anger over allegations that she siphoned profits from diamond mines and bought luxury palaces. She spent so much money on foreign trips that the European Union imposed sanctions on the Mugabes to stop them from sucking wealth out of the country.

The couple appear to have now fallen from power, as the military on Tuesday night took Mr. Mugabe, 93, the world’s oldest head of state, into custody. His wife’s whereabouts were not clear on Wednesday, but there were reports that she was in Namibia when the apparent coup unfolded.

Despite deep unpopularity across the country, Zimbabwe’s first lady managed to vault herself to the center of a vicious internal battle to succeed her husband.

A skilled operator, she led a revolt by a younger faction of politicians — known as G-40 because many of its members were in their 40s — who posed a stark challenge to the authority of the veterans of Zimbabwe’s struggle for independence from white-minority rule.

The divide has been generational and personal.

Mrs. Mugabe has been a fierce defender and accomplice of her husband — she once claimed he could still run the country “as a corpse” — as he ruthlessly ousted two successive vice presidents, Joice Mujuru and Emmerson Mnangagwa, who were rival claimants to the presidency.

Above all, she has emerged as a champion of her own presidential aspirations as her husband’s health has visibly declined.

“They say I want to be president,” she told the recent party rally. “Why not? Am I not a Zimbabwean?”

To her opponents, Mr. Mugabe’s dismissal of Mr. Mnangagwa last week might have been the last straw. Mr. Mnangagwa, like Mr. Mugabe, was a veteran of Zimbabwe’s liberation movement, but he was discharged for “disloyalty, disrespect, deceitfulness and unreliability.” He has not been heard from, and rumors are rife that he might have fled to South Africa.

Mr. Mnangagwa, 75, retains widespread support within the military, in contrast to Mrs. Mugabe. The two made no secret of their enmity: He accused her of trying to kill him with poison-laced ice cream and seizing power for herself in order to protect the Mugabe family’s assets.

“Why would I kill him?” she is reported to have replied to the accusations. “I can’t prepare one cup of an ice cream to kill Mnangagwa. Who is he? I am the wife of a president!”

Dissatisfaction at Mrs. Mugabe spilled into the open recently. “We hate what you’re doing,” protesters chanted recently at a rally of the Mugabes’ governing party, ZANU-PF, before they were arrested and charged with undermining the president’s authority.

Mrs. Mugabe is hardly the first political spouse to draw ire — much of it aimed, or intended, for her husband — but her flamboyance has set her apart and made it easier for opponents to build a case against her, said Stephen Chan, professor of world politics at the School of Oriental and African Studies, University of London.

“Grace Mugabe became a Lady Macbeth in the Zimbabwean soap opera: She led her ailing and aged husband to make his fatal miscalculation that he could stand in the face of united military opposition,” Mr. Chan said. “Neither thought the army would move as it did. Neither announced anything resembling a coherent economic plan to help the impoverished citizens of the country — including increasingly impoverished regular soldiers of the army who, needing to feed their families, cooperated with the plans of their senior officers for the coup that saw the first couple’s fall from grace.”

Grace Mugabe was born in South Africa in 1965, the same year that a white-led government proclaimed the independence of what was then Southern Rhodesia from Britain, triggering international condemnation and an armed struggle. She moved to Zimbabwe as a child. She was 14 when the new nation of Zimbabwe, led by Mr. Mugabe, was born in 1980 after a political settlement had been reached.

The two met in the late 1980s when Mrs. Mugabe was working as a secretary for Mr. Mugabe. They were each married at the time: she to an Air Force pilot with whom she had a son, and he to a teacher and political activist.

The first Mrs. Mugabe died in 1992, and Grace married Robert Mugabe in 1996, after she divorced her first husband, now a defense attaché at the Zimbabwean Embassy in China.

The press nicknamed Mrs. Mugabe “Gucci Grace” and “Dis-Grace” for her shopping trips. During a trip to Paris in 2002, she was reported to have spent $120,000. She is also said to have purchased multimillion dollar properties in South Africa and built luxury palaces after pillaging party coffers. Earlier this year, she was widely panned for having spent $1.4 million on a diamond ring.

Mrs. Mugabe has denied reports of corruption, but without offering specifics.

“It’s impossible for one to spend a million dollars in an hour,” she said in an interview for a South African documentary. “I don’t have time for all these things to pamper myself.”

Asked what was the most she had ever spent on clothing in one day, she demurred, acknowledging only that she liked to buy fabrics with which to design her own clothing.

The Mugabes have two sons and a daughter; none has expressed interest in politics.

In 2014, after Mr. Mugabe ousted Mrs. Mujuru, Mrs. Mugabe swiftly climbed the rungs of power. She was elevated by her husband as the head of the ZANU-PF’s women’s league, which gave her a seat on the governing party’s decision-making body.

She was granted a doctorate in sociology from the University of Zimbabwe, even though she was enrolled for a few months but just enough time to give her the necessary credentials. (Her husband was the university’s chancellor.)

This summer, she became the subject of a diplomatic incident when a 20-year-old South African model accused Mrs. Mugabe of beating her with an electrical cord. Mrs. Mugabe was allowed to return home after being given diplomatic immunity by South Africa, a move that was widely criticized. (Mrs. Mugabe has denied the accusations.)

Mrs. Mugabe has credited her husband for her career. “He took time to groom me into the woman that I am now,” she said in a speech.

Asked in the documentary about the vociferous criticisms of her, she replied: “I don’t even care. Ignorance is bliss.”