Sean O’Casey (1880-1964), Irish dramatist, whose successful Dublin trilogy rescued the Abbey Theatre from financial ruin in the 1920s. He was born in Dublin's inner city, one of the worst slums in Europe at the time, and his father died in 1886. His mother then supported the large family, and she later became the model for O'Casey's tenement heroines. O'Casey suffered from a painful eye condition that afflicted him all his life, but he read voraciously to make up for missed schooling. He began working at age 14, primarily for the railroads, and was active for several years in the labor movement and in the nationalist struggle against Britain’s rule of Ireland.

O'Casey's early plays were rejected by the Abbey Theatre, a national repertory company in Dublin that specialized in producing Irish works. But Lady Gregory, one of the Abbey’s directors, encouraged him to continue submitting his work. In 1923 the Abbey accepted The Shadow of a Gunman, the first play of O'Casey's Dublin trilogy. The play is based on his experience living in a house that was raided by British forces. It contrasts Donal Davoren, who pretends to be a gunman and is the prototype for O'Casey's romantic heroes, with the true hero of the story, Minnie Powell. The Shadow of a Gunman introduced a gallery of characters from the slums whose rich, witty conversation enabled them to transcend their impoverished lives. It was an instant success.

Juno and the Paycock (1924), second in the trilogy, followed a similar formula, depicting a braggart (the Captain), a heroic woman (Juno), tenement characters, and Dublin during Ireland’s 'troubles' (its fight for independence during the early 20th century). The Boyle family expects an inheritance that will change their lives. When it proves to be worthless, the gallant Juno gathers her daughter, who has been seduced and abandoned, and leaves to start a new life. Juno and the Paycock, like The Shadow of a Gunman, was enormously successful. The final play of O’Casey’s trilogy, The Plough and the Stars (1926), is set in a Dublin tenement during the 1916 Easter Rebellion (an Irish uprising against the British). Again there is a contrast between romantic idealism, embodied here by Irish Citizen Army officer Jack Clitheroe, and the real heroism and suffering of the poor civilians of the city. Written just ten years after the Rebellion, the play's criticism of nationalistic idealism caused a riot.

After 1926 O'Casey lived in England. He broke with the Abbey Theatre when poet William Butler Yeats, an Abbey director, refused The Silver Tassie (1928), an antiwar play. O'Casey wrote other plays with social and political themes, including Within the Gates (1934), The Star Turns Red (1940), Red Roses for Me (1942), and The Purple Dust (1945). Most of these appeared in England, but The Purple Dust was staged in Ireland. Irish productions of his later works included Cock-a-Doodle Dandy (1949), The Bishop's Bonfire (1955), and The Drums of Father Ned (1959), which ignited controversy when the Roman Catholic clergy objected to its criticism of the Catholic Church’s social domination of Ireland. While some of the later plays have their supporters, critics agree that O'Casey's reputation rests on the Dublin plays, particularly Juno and Plough.

O'Casey also wrote essays, theater criticism, and his Autobiographies (1963), originally published in six volumes from 1939 to 1954. Using different kinds of narrative devices, Autobiographies gives the author’s impressions of his life rather than a conventional, factual account of it.