Sean O'Casey (March 30, 1880 – September 18, 1964) was a renowned Irish dramatist known for his realistic portrayals of Dublin's working-class life and social conflicts. Born into a poor Protestant family, he experienced hardship early and engaged in labor and trade union activism. His major works include Juno and the Paycock, The Plough and the Stars, and The Silver Tassie. O'Casey's plays blend tragedy and comedy, reflecting the struggles of Irish independence and human nature. He later moved to England and continued writing until his death, leaving a lasting impact on 20th-century theater.