Mitchell, Susan Langstaff (1866–1926), essayist and poet, was born 5 December 1866 at the Provincial Bank House, Main St., Carrick-on-Shannon, Co. Leitrim, fifth among seven children of Michael Thomas Mitchell, bank manager, and Kate Mitchell (née Cullen). The death of her father (1873) and her mother's impecuniosity led to her adoption by three paternal aunts in Co. Dublin, while the rest of the family moved to Sligo. Educated at Morehampton House School, she took the TCD women's examination with honours. In 1884 she moved to Birr, King's Co. (Offaly), to be with her aunts but, although a protestant, she soon rebelled against their unionist beliefs and became a supporter of home rule. During her visits to her mother in Sligo she encountered William Butler Yeats (qv), and they quickly became friends. In 1897 she began teaching in Sligo, but it was an unhappy time for her: her fiancé, Douglas Crook, died and she was diagnosed with tuberculosis. Moving to London for treatment of a hearing condition, she stayed with the Yeats family and had her portrait painted (1899) by John Butler Yeats (qv). Returning to Ireland, she became in 1901 sub-editor of the Irish Homestead, the newspaper of the Irish Agricultural Organisation Society (IAOS).
Displaying a ready wit and a natural ability for writing, she wrote many essays and book reviews, and became lifelong friends with George Russell (qv), (AE) who valued her writing highly. With his encouragement, she published some of her poems in an anthology, A Celtic Christmas (1902), and in 1908 wrote two complete works: The living chalice, a collection of spiritual poetry, and Aids to immortality of certain persons in Ireland, which contained brilliant examples of her witty verse. A third collection, Frankincense and myrrh, followed in 1912.
A popular and well known figure in Irish literary circles, she attacked W. B. Yeats's theatre policy in an article in Sinn Féin in 1909. Unafraid of causing offence to friend or foe, she examined critically the character of George Moore (qv) in a biography she published in 1916; she had a wicked sense of humour, and had satirised Moore's pomposity in previous works. Nor was she afraid of poking fun at her friends, and both AE and W. B. Yeats suffered from her pen, although neither held it against her. A supporter of Sinn Féin, she was a founder member and served on the executive of the United Irishwomen (later renamed the Irish Countrywomen's Association), composing a song, ‘To the daughters of Erin’ to honour its members. In the aftermath of the 1916 rising she looked after the personal affairs of Countess Markievicz (qv), and became increasingly critical of the British government. In 1921 AE appointed her assistant editor of the Irish Statesman, and she wrote some of her best journalistic pieces, including book and theatre reviews, in this period.
She died 4 March 1926 of cancer and was buried at Mount Jerome cemetery, Dublin; she did not marry. In her obituary in the Irish Statesman AE called her ‘a woman of genius’ and ‘one of the best Irish women of her time’(quoted in Kain, 16). Her 1899 portrait by John Butler Yeats is in the NGI.