In Rising Damp he played Rigsby, the lecherous landlord of a house converted to a block of seedy bedsits.
Another famous role was in The Fall and Rise of Reginald Perrin, adapted by David Nobbs from his own Reginald Perrin comic novels, in which he played the title character.
In the 1970s he starred alongside Joan Collins as her bumbling suitor in a series of Cinzano commercials.
In the animated adaptation of The Perishers he played the voice of Boot the dog.
He also played the title role in the short film Le Petomane, but his most widely-seen appearance may be as a Russian general, Smyslov, in Stanley Kubrick's 2001: A Space Odyssey (1968).