Films:
* The Purple Plain (1954): Played an officer in the Royal Air Force during World War II.
* The Great O'Malley (1955): Portrayed the Irish chieftain Grace O'Malley.
* The Adventures of Robin Hood (1953): Appeared as a member of Little John's gang.
* The Bridge on the River Kwai (1957): Played a British officer who works on the bridge.
* The Sundowners (1960): Played a sheep rancher in Australia.
* The Guns of Navarone (1961): Played the role of a Greek fisherman.
* The Inspector (1962): Played a police inspector.
* The Long Ships (1964): Portrayed a Viking chieftain.
* The Charge of the Light Brigade (1968): Played a British officer in the Crimean War.
* The Italian Job (1969): Played a gold-plated safe expert.
* The Day of the Jackal (1973): Portrayed a French police official.
* The Odessa File (1974): Played the role of a German official.
* The Duellists (1977): Portrayed a Russian nobleman.
* Gandhi (1982): Played a lawyer who assists Gandhi.
* The Killing Fields (1984): Played the role of a Cambodian journalist.
* My Left Foot (1989): Played a doctor who cares for Christy Brown.
* The Play's the Thing (1989): His last film appearance, playing the role of a general manager.
Television:
* The Adventures of Robin Hood (1955-1959): Played Friar Tuck.
* The Prisoner (1967-1968): Played the role of the Number Two in several episodes.
* The Saint (1962-1969): Appeared in several episodes.
* The Avengers (1961-1969): Appeared in several episodes.
* The Forsyte Saga (1967): Portrayed the role of Jolyon Forsyte.
* The Jewel in the Crown (1984): Played the role of a British official in India.
* The Irish R.M. (1986-1990): Played the role of Father O'Malley.
This is just a selection of Cyril Cusack's extensive work. He was known for his versatility and his ability to portray both comic and dramatic roles. He was also a prolific stage actor, appearing in many plays throughout his career.
To learn more about his work, you can find detailed information on his filmography on websites such as IMDb and Wikipedia.