- Attended Terenure College, where he began acting in the school's theater program.
- Returned to Ireland after graduating from the Royal Academy of Dramatic Art to begin his career as a theatre actor before moving into television and film.
- Was part of the original cast of the play The Seafarer when it premiered on the West End in 2006; when the play transferred to Broadway, his role was recast with Sean Mahon.
- Appeared in the play The Night Alive at the Donmar Warehouse in 2013, opposite Ciarán Hines and Jim Norton.
- Joined Game of Thrones during the show's second season, as the recurring character Roose Bolton; was promoted to a series regular for season six.