Catherine Cusack (born 21 December 1968, London) is an English actress. She is the half-sister of the actresses Sinéad Cusack, Sorcha Cusack and Niamh Cusack, and the fourth daughter of the Irish actor Cyril Cusack and his second wife Mary Rose Cunningham, their only child together. She was accepted to study at Royal Holloway and Bedford New College, but became a stage manager at the Tricycle Theatre in London. She made her professional debut in Brendan Behan's play The Hostage before making her television debut in the BBC series Sophia and Constance.