Cyril Cusack (26 November 1910 - 7 October 1993) was an Irish actor, born in Natal, South Africa. He was the son of a sergeant in the mounted police and an actress. His parents separated when he was young and his mother took him to England, and then to Ireland. Cusack's mother and her partner, Breifne O'Rorke , joined the O'Brien and Ireland Players. Cyril made his first stage performance at the age of seven. Cusack was educated in Newbridge, Kildare, and University College, Dublin. He left without a degree and joined the Abbey Theatre in 1932. Between then and 1945 he performed in over sixty productions, particularly excelling in the plays of Sean O'Casey. In 1947 Cusack formed his own company and staged productions in Dublin, Paris and New York City.

In 1963 he joined the Royal Shakespeare Company in London and appeared there for several seasons. By this stage he had established a successful career in films. In 1977 Cusack's wife, Maureen Kiely , an actress, died. Two years later in 1979 he married Mary Rose Cunningham . He received honorary doctorates in 1977 and 1980 from the NUI and the University of Dublin respectively. In 1984 he appeared as the shop-keeper and Thought Police spy Charrington in the film version of George Orwell's Nineteen Eighty-Four. In 1989 his performance in the film My Left Foot, with Daniel Day-Lewis, contributed to its success. Cusack's last stage performance was in Chekhov's The Three Sisters, in which three of his daughters played the sisters. His four daughters, Niamh , Sorcha , Sinéad and Catherine are actresses. His sons, Paul and Pádraig, work as a producer with RTÉ and in computers, respectively.