Quatermass II is a British science fiction serial, originally broadcast by BBC Television in the autumn of 1955. It is the second in the Quatermass series by writer Nigel Kneale, and the oldest of those serials to survive in its entirety in the BBC archives.

The serial sees Professor Bernard Quatermass of the British Experimental Rocket Group being asked to examine strange meteorite showers. His investigations lead to his uncovering a conspiracy involving alien infiltration at the highest levels of the British government. As even some of Quatermass's closest colleagues fall victim to the alien influence, he is forced to use his own unsafe rocket prototype, which recently caused a nuclear disaster at an Australian testing range, to prevent the aliens from taking over mankind.

Although sometimes compared unfavourably to the first and third Quatermass serials, Quatermass II was praised for its allegorical concerns of the damaging effects of industrialisation and the corruption of governments by big business. It is described on the British Film Institute's Screenonline website as "compulsive viewing".