Rossiter broke into film roles by using Billy Liar in which he plays the title character's boss. This brief role fixed him by using audiences as an typically blemished & rigid authority figure.

Around Rising Damp he played Rigsby, the lecherous landlord of the home converted to a prevent of seedy bedsitter. A second far-famed 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 a title character.

In the Seventies he starred alongside Joan Collins as her bumbling wooer inside the series of Cinzano commercials, in which somehow a swallow would become spilled down the female character's dress.

In the alive adaptation of The Perishers he provided the voice for Boot the dog. His survive TV role was that of the eponymic supermarket manager in ''Tripper's Day, an ITV sitcom which was not up to the standards of the shows he had previously adorned.

He likewise played a name part in the short film Le Petomane'', but Rossiter's virtually all widely-seen appearance can be his brief turn when a Russian scientist Smyslov around Stanley Kubrick's 2001: A Space Odyssey (1968). Rossiter went within to play a memorable a portion of Captain John Quinn in Kubrick's Barry Lyndon (1975) and as well appeared within Water.

Rossiter died of the heart attack in 1984 while waiting to last onstage at a Lyric Theatre, London, where he was performing within Joe Orton's play Loot. He left behind his 2nd married woman Gillian (he got antecedently been married to actress Josephine Tewson) and the girl Camilla.