O'Brien, Máire (‘Máire Rua’) (1615?–1686), Gaelic aristocrat and figure in Irish folklore, was daughter of Sir Torlach Rua MacMahon, lord of East Corcabaskin or Clonderlaw, and his wife Mary, youngest daughter of Conor O'Brien (qv), 3rd earl of Thomond. Torlach Rua had a reputation for ferocity that would pass to his daughter. In 1839 John O'Donovan (qv) collected these lines about Torlach Rua in west Clare: ‘Torlach Rua, the betrayed, the liar killed his wife and child together’. Although an elegy to Máire Rua places her birth at Bunratty, she was probably born at Clonderlaw. O'Brien family tradition places her birth at Urlan More; however, it is likely that she was fostered there rather than born there. A marriage was arranged (1634) between Máire Rua and Daniel Neylon, a substantial north Clare landowner. When Neylon died (1639) and left her with three young sons, Máire Rua managed the extensive Neylon property until her son William came of age.
Folklore about Máire Rua describes her many marriages: she was said to have had between twelve and twenty-five husbands, all of whom she killed, one by kicking him to death. She did, in fact, marry Conor O'Brien of Leamaneh within seven months of Neylon's death. They built an imposing addition to the O'Brien tower house at Leamaneh, on the edge of the Burren in Co. Clare. An inscribed stone in the Leamaneh porch, now in the garden of Dromoland Castle, carries their son Donough's baronet arms. It reads: ‘This was built in the year of Our Lord 1648 by Conor O'Brien and Mary ní Mahon alias Brien wife to the said Conor.’ The scale of the house, its broad façade, formal gardens, fish pond, and deer park, anticipated a life of peace and prosperity. Conor and Máire Rua had eight children. Donough, their eldest son and heir, was born in 1642.
The folklore about Máire Rua's ferocity and lust are associated with her Leamaneh years, where she is described as keeping twelve or twenty-five men servants dressed as women and hanging them from the corbels of Leamaneh. She also is said to have exacted tolls or preyed on passers-by or trespassers. Máire MacNeill (qv) (1904–87) traced the local legends of her challenges to suitors to ride a wild stallion to an earlier mythological tradition, a version of the sovereign-goddess myth.
During the war (1641–52) Conor financed and led one of Clare's five militia companies. They raided the tower houses of English and Dutch settlers. Named in settlers’ depositions concerning the siege of Barntick castle, where livestock was taken and a servant killed, Máire Rua was later charged with his murder.
In 1650 Conor was commissioned colonel of horse in the army of Charles II. The following year he died from wounds received in an encounter with Gen. Edmund Ludlow (qv) at the pass of Inchecrogan. The legendary account of Máire Rua describes her leaning out of a Leamaneh window, shouting down to the party of men carrying home Conor's body: ‘We want no dead men here’, dressing in blue silk and lace, driving to the Limerick camp of Cromwell's western commander, Gen. Henry Ireton (qv), and proclaiming that she was prepared to marry any one of Ireton's officers.
She did move quickly after Conor's death, but she went north to Conor's commander, Ulick Burke (qv), Lord Clanrickard, Charles I's lord deputy in Ireland. Within a week of Conor's death, Máire Rua petitioned Clanrickard to be the custodian of Conor's estate. While she succeeded in holding Conor's land for her O'Brien children as she held the Neylon property for her Neylon sons, she was not able to save Leamaneh. After Limerick fell to the Cromwellians, the army moved north and turned Leamaneh into a garrison. Máire Rua did marry a third time. The record of a 1653 land transaction lists her as the wife of John Cooper , a land speculator, entrepreneur, and former parliamentary officer who may have resided with Máire Rua in Limerick, and whom she was reputed to have dispatched with a kick.
The restoration would seem to have promised prosperity for Máire Rua, the widow of one of Charles II's officers; however, the 1642 depositions concerning the siege of Barntick were produced, and Máire Rua was indicted for murder. Though she was granted a royal pardon in 1662, the trial went ahead, and it dragged on for years. Máire Rua's November 1665 letter to Henry O'Brien (1621–91), 7th earl of Thomond, spoke of ‘my extremitie & troubles in England’.
A woman with Máire Rua's reputation had to have an extraordinary death. One legend says she was hung by her own hair from a tree in Toonagh Wood, a place she is believed to haunt; another has her walled up in a hollow tree in Carnelly. In fact, her end was more conventional. In poor health but ‘yet of perfect memory’, she signed her will on 7 June 1686. While she had controlled thousands of acres, it is not the will of a wealthy woman. She asked to be buried in the abbey of Ennis. There is no marker, but it is likely she is buried there beside Conor O'Brien. A portrait of Máire Rua holding a key, an appropriate symbol for a property-conscious woman, is in the possession of the O'Brien family; the O'Brien arms in the upper left corner date it to her years with Conor. Another portrait of an older Máire Rua, painted in restoration style, hangs in Dromoland Castle Hotel.