William O'Brien was a politician and trade unionist in Ireland. While rarely dominating the political spotlight, O'Brien was incredibly powerful and influential behind the scenes, maintaining a firm grip over Ireland's trade unions for many decades. Besides his leadership in the trade unions, O'Brien was a founder, alongside James Larkin and James Connolly, of the Labour Party of Ireland. In later years a rift formed between Larkin and O'Brien that would last the rest of their lives and often divide the labour movement in Ireland.
- Occupation
- politician, trade unionist
- Position held
- Teachta Dála, Teachta Dála, Teachta Dála
- Citizenship
- Ireland, Irish Republic, Irish Free State
- Born
