Seán O'Casey (born John Casey, 30 March 1880 – 18 September 1964) was an Irish dramatist and memoirist. A committed socialist, he was the first Irish playwright of note to write about the Dublin working classes.
O'Casey was born in Dublin, Ireland, as John Casey or John Cassidy to Michael and Susan Archer Casey in a house at 85 Upper Dorset Street, in the northern inner-city area of Dublin. It is commonly thought that he grew up in the working class society in which many of his plays are set. In fact, his family were considered as "shabby genteel". He was a member of the Church of Ireland, baptised on July 28, 1880 in St. Mary's parish, confirmed at St John the Baptist Church in Clontarf, and an active member of Saint Barnabas until his mid-twenties, when he drifted away from the church.
O'Casey's father died when Seán was just six years of age, leaving a family of thirteen. The family lived a peripatetic life thereafter, moving from house to house around north Dublin. As a child, he suffered from poor eyesight, which interfered somewhat with his early education, but O'Casey taught himself to read and write by the age of thirteen.
He left school at fourteen and worked at a variety of jobs, including a nine-year period as a railwayman. O'Casey worked in Easons for a short while, in the newspaper distribution business, but was sacked for not taking off his cap when collecting his wage packet.
From the early 1890s, O'Casey and his older brother, Archie, put on performances of plays by Dion Boucicault and William Shakespeare in the family home. He also got a small part in Boucicault's The Shaughraun in the Mechanics' Theatre, which stood on what was to be the site of the Abbey Theatre.