Mary Devenport O'Neill, poet and playwright, was initially a student of art. Born in Galway and educated in Dublin at the Dominican Convent in Eccles Street and at the Metropolitan School of Art, she was a talented painter, but later turned to literature as her sole artistic focus. Married to the writer Joseph O'Neill and settled in Dublin, she was a friend of W. B. Yeats and a member of George Russell's literary circle before forming her own salon. This would become an important focus for a number of important writers, including Frank O'Connor, Padraic Colum and Francis Stuart. She was interested in mysticism and it was this that formed an important dimension of her friendship with Yeats. She wrote verse-plays and collaborated with Austin Clarke in their production. Though a talented poet, she produced just one full collection—Prometheus and Other Poems—in 1929. This work was justly praised for its understated emotional tones and is inflected by the minimalism associated with modernism, as well as by a significant mode of existential enquiry. She contributed occasionally to the Irish Times, The Bell and the Dublin Magazine.