Butler, Mary Ellen Lambert (1873–1920), novelist, was born 28 June 1873 in England, the youngest of the two daughters and a son of Peter Butler (1840–80) of Bunnahow House, Co. Clare, and Mary Ryan of Tipperary. The Butlers were landowners who remained catholic. Through intermarriage, there were a significant number of protestant relatives; Butler's grandfather William (III) Butler (1809–1843) married Ellen Lambert of Castle Ellen, Athenry, Co. Galway, and Ellen's sister, Isabella, was the mother of Edward Carson (qv). Mary was educated by a resident governess and later attended Alexandra College in Dublin in the late 1880s, traditionally a college for protestant girls. She was fluent in several European languages and her father spoke several languages at home. The family was strongly loyal to the crown, and the children brought up in the traditional gentry lifestyle; both Mary and her sister were presented at Dublin Castle to mark their ‘coming out’. Although the Butlers were considered good landlords, they were affected by the land war of 1879–81 and increasingly regarded it and agrarian violence as synonymous. The death of Mary's brother William in 1886 brought the line of male heirs to an end; Bunnahow House was sold and the family moved to Dublin.
Butler attributed her nationalism to the books of Charles Gavan Duffy (qv) and Thomas Davis (qv), which she found in a friend's home. From this moment, she turned her back on her family traditions, joined the Gaelic League, and attended Irish language classes with Colonel Maurice Moore (qv), brother of George Moore (qv). She immersed herself in Irish Ireland and like many others visited the Aran Islands on several occasions to experience their ‘authentic Irish atmosphere’ (NLI, MS 7321). Through these trips she became friendly with Patrick Pearse (qv) and Thomas Concannon (1870–1961). On the Aran Islands, she met her husband, Thomas O'Nolan, MA, whom she married in 1907. She was active in the Gaelic League, served on the league's executive (1903–7), and contributed to the league's paper, An Claidheamh Soluis.
Her publications included Irishwomen and the home language (1900), Two schools: a contrast (n.d.), A bundle of rushes (1900) and The ring of day (1907). Her novel, The ring of day, was first serialised in the Irish Peasant in 1906 and later published in 1907. In her writings, Butler concentrated on the role of Irishwomen and the Irish language movement, advocating that it was the mission of Irish mothers to make Ireland Irish again. Rather than the schools being the centre of the Irish language campaigns, it should be rooted in the homes and mothers of Ireland. She abhorred any public role for women, asserting that Irish women were by nature dignified and decorous. Thus, Butler made the domestic sphere central to the creation of a national life. She turned the restriction of most women in the home into a virtue, by asserting that the nation could not be created without their commitment.
A member of the nationalist women's organisation, Inghinidhe na hÉireann, in 1904 she met Arthur Griffith (qv) for the first time, when she went to his office to submit an article to his paper, United Irishman. During the meeting Griffith explained his vision of self-sufficiency for Ireland, when Butler interjected: ‘why a Sinn Féin policy?’ Griffith later wrote to her sister upon her death that ‘it was she who suggested the name Sinn Féin to me, one day at the end of 1904. Her name will be ever linked with its history’ (NLI, MS 7321). However, the term Sinn Féin was not a new one; it had already been used in the early days of the Gaelic League, and possibly even before that. Griffith was a formative influence on Butler's politics and he advised her on what history books to read. In 1905 she attended the first convention of Sinn Féin, and she became a regular contributor to United Irishman. She also contributed to the Weekly Independent with an educational column on Irish for young children called ‘Eire Óg’ (her pen name was Sean Mathair) and wrote for Nationality and some Irish-American papers.
Following her husband's death in December 1913, Butler withdrew from her nationalist activities until early 1916. In summer 1916 she campaigned with Colonel Maurice Moore for a reprieve for Roger Casement (qv). In January 1919 she received tickets from both Eoin MacNeill (qv) and George Gavan Duffy to attend the first dáil. In 1920 she went to visit her sister who was a nun in Rome. During her visit she suddenly became ill and died on 27 November 1920, and was buried in Rome.