Sean O’Casey’s first produced play, The Shadow of a Gunman was submitted to the Abbey Theatre in 1922, the publication year of James Joyce’s Ulysses and T. S. Eliot’s The Waste Land. He was a contemporary of modernists including Woolf, Pound, and Eliot, yet O’Casey’s work is rarely considered in accounts of modernism. This chapter considers how figures including Samuel Beckett, Denis Johnston, and Katharine Worth have offered a consideration of O’Casey that looks past the quasi-realistic surface of his early work to find a dramatist of experimentalism and of sardonic humour who produced creative work that coincides with modernism yet that resists critical categories.