Ieuan Rhys was born Ieuan Rhys Evans on 24 December 1961 in the village of Trecynon, near Aberdare in South Wales. He was raised speaking Welsh and attended Ysgol Gynradd Gymraeg Aberdar primary school and Ysgol Gyfun Rhydfelen secondary school near Pontypridd, both Welsh-medium schools; his father, Gethin Evans, was a music teacher at the local comprehensive school. Rhys trained as an actor at the Royal Welsh College of Music and Drama in Cardiff.
He became a familiar face across Welsh television, playing Sergeant Glyn James in the BBC Cymru soap opera Pobol y Cwm for thirteen years, and Sergeant Tom Swann in the final series of A Mind to Kill for Channel 5. He also hosted six series of Sion a Sian, the Welsh-language version of the game show Mr and Mrs, for HTV, and played deputy headmaster Eurig Bell in S4C's Gwaith/Cartref.
Rhys has built an extensive stage career, frequently working with director Michael Bogdanov, including productions of Romeo and Juliet and a run of five Shakespeare productions between 2001 and 2004. His other theatre credits include work for the National Theatre in London, National Theatre Wales, and numerous seasons at Aberystwyth Arts Centre, alongside regular pantomime work across theatres in England and Wales. His film credits include Darklands and The Englishman Who Went Up a Hill But Came Down a Mountain, opposite Hugh Grant.
Beyond acting, Rhys is a published author, having written an autobiography, Allet Ti Beswch!, and several Welsh-language children's books, and has recorded two albums for the Fflach label. He lives in Cardiff.