Kieron Moore grew up in County Cork in an Irish-speaking household. His father, Peadar Ó hAnnracháin (born 1873) (also known as Peter/Peadar Hourihane and Peadar O’Hourihane) was a writer and poet, and a staunch supporter of the Irish language. Peadar, a son of Seaghan Ó hAnnracháin (born 1834) and Máire Ní Dhonabháin (also born 1834) and who was one of the first organisers for Conradh na Gaeilge (Gaelic League), was twice imprisoned by the British during the Irish Civil War. Peadar lived with his parents and his sister, Áine Ní Annracháin (born 1885), and his niece, Máirín Ní Dhiomasaig (born 1903), at 14 Poundlick, Skibbereen, County Cork in 1911. He also wrote for the Southern Star newspaper for many years and had been its editor. Several members of Kieron’s family pursued careers in the arts. His sister Neasa Ní Annracháin was a stalwart of the Raidió Éireann Players, while his brother, Fachtna, was director of music at the station, and a second sister, Bláithín Ní Annracháin, played the harp with the National Symphony Orchestra. Following his family’s move to Dublin, Moore attended Irish language school, Coláiste Mhuire. Later, his medical studies at University College Dublin were cut short when he was invited to join the Abbey Players. In 1947, he married Barbara White, with whom he had four children.

Living in Britain for years, Kieron Moore made more than 50 film appearances and acted in several British television episodes. Beginning his acting career at the Abbey Theatre in Dublin, he made his British stage debut at the age of 19 as Heathcliff in a production of Wuthering Heights, later starring in a BBC TV production of the play (1948). His first film role was as an IRA man in The Voice Within (1945). Adopting the stage name Kieron Moore, he was cast in a leading role in A Man About the House in 1947. His next role, in the psychological thriller Mine Own Executioner (1947), confirmed his potential, but he was widely seen as seriously miscast when he took on the role of the suave Count Vronsky in Julian Duvivier’s production of Anna Karenina (1948), which starred Vivien Leigh and Ralph Richardson, receiving the worst notices of his career. Despite this setback, Moore was invited to Hollywood, where in 1951 he made two films, playing Uriah the Hittite in the biblical epic David and Bathsheba and a Foreign Legion corporal in Ten Tall Men, starring Burt Lancaster. He also featured in Mantrap (1953), Recoil (1953), and The Blue Peter (1954). In 1959, Kieron Moore appeared in Darby O’Gill and the Little People. The following year, he gave an impressive performance in the comedy-thriller The League of Gentlemen (1960), playing a homosexual former fascist and army officer recruited to take part in a big robbery. There followed roles in The Siege of Sidney Street (1960), shot on location in Ireland, Doctor Blood’s Coffin (1961), The Thin Red Line (1964), and Arabesque (1966). In his final film, Custer of the West (1967), he played Chief Dull Knife. He also made television appearances in Fabian of the Yard, Jason King and Randall and Hopkirk (Deceased) which aired in 1970 in episode 16 When the Spirit Moves You, where he was cast as the villain Miklos Corri. Anton Rodgers, another actor who died in 2007, also appeared in that episode. Moore also took on the starring role in Ryan International, which he also wrote.

Kieron Moore quit acting in 1974, becoming a social activist on behalf of the Third World. He joined CAFOD (Catholic Agency for Overseas Development), with which he worked for nine years. During that time he made two film documentaries, Progress of Peoples (Peru) and The Parched Earth (Senegal). Later, as projects manager, he travelled to the Middle East and India. He next became associate editor of The Universe, editing the supplement, New Creation, which he transformed into the magazine New Day. He last worked for television, providing voice-overs for Muiris Mac Conghail’s RTÉ documentaries about the Aran Islands and the Blaskets. Moore retired in 1994 to the Charente-Maritime in France, where he joined the church choir, became a hospital visitor, and enjoyed reading French, Spanish, English and Irish literature. He is survived by his wife, the former actress Barbara White, who played opposite him in The Voice Within and Mine Own Executioner, their daughter Theresa (Soeur Miriame-Therese) and sons Casey, Colm and Seán.