Professor Bernard Quatermass is a fictional character, originally created by the writer Nigel Kneale for BBC Television. Quatermass appeared in three influential BBC science fiction serials of the 1950s (The Quatermass Experiment, Quatermass II, and Quatermass and the Pit), and returned in a final serial for Thames Television in 1979 (Quatermass). A remake of the first serial appeared on BBC Four in 2005.

The character also appeared in films, on the radio and in print over a fifty-year period. Kneale picked the character's unusual surname from a London telephone directory, while the first name was in honour of the astronomer Bernard Lovell. Quatermass is an intelligent and highly moral British scientist, who continually finds himself confronting sinister alien forces that threaten to destroy humanity. In the initial three serials he is a pioneer of the British space programme, heading up the British Experimental Rocket Group.

The character of Quatermass has been described by BBC News Online as Britain's first television hero, and by The Independent newspaper as "A brilliantly conceived and finely crafted creation... [He] remained a modern 'Mr Standfast', the one fixed point in an increasingly dreadful and ever-shifting universe." In 2005, an article in The Daily Telegraph suggested that "You can see a line running through him and many other British heroes. He shares elements with both Sherlock Holmes and Ellen MacArthur."