The Tommy Shelby actor was born in Cork in 1976 to a mother who taught French, while his father, Brendan, worked as a schools inspector before moving to the Department of Education. His grandfather, aunts and uncles were also teachers.
But not wanting to follow the family tradition of working in education, Cillian pursued a career in the arts after getting a 'huge high' from his drama module at Catholic secondary school Presentation Brothers College.