X the Unknown
I expected trash, and I was surprised. It was intended to be a sequel to The Quatermass Xperiment (US title: The Creeping Unknown), but the author of the Quatermass stories refused to let the name be used. The science, of course, is just gibberish, but the production looks pretty good, the script is miles ahead of American horror pictures of the time, and the acting is competent. The British are just better at this sort of thing, bringing a sense of realism even to an outlandish situation. X, when we finally see it, is a less-convincing version of the Blob, but as this is in black and white it doesn’t seem to matter all that much.